Add the i18n-tasks gem

This can be used for checking our translations, for example to see
if there are unused translations in en.yml

Gemfile

@@ -137,6 +137,7 @@ group :development do
   gem "better_errors"
   gem "binding_of_caller"
   gem "debug_inspector"
+  gem "i18n-tasks"
   gem "listen"
   gem "vendorer"
 end

Gemfile.lock

@@ -232,12 +232,24 @@ GEM
       activesupport (>= 5.0)
     hashdiff (1.0.1)
     hashie (5.0.0)
+    highline (2.1.0)
     htmlentities (4.3.4)
     http_accept_language (2.1.1)
     i18n (1.12.0)
       concurrent-ruby (~> 1.0)
     i18n-js (3.9.2)
       i18n (>= 0.6.6)
+    i18n-tasks (1.0.12)
+      activesupport (>= 4.0.2)
+      ast (>= 2.1.0)
+      better_html (>= 1.0, < 3.0)
+      erubi
+      highline (>= 2.0.0)
+      i18n
+      parser (>= 2.2.3.0)
+      rails-i18n
+      rainbow (>= 2.2.2, < 4.0)
+      terminal-table (>= 1.5.1)
     image_optim (0.31.3)
       exifr (~> 1.2, >= 1.2.2)
       fspath (~> 3.0)
@@ -488,6 +500,8 @@ GEM
       sprockets (>= 3.0.0)
     strong_migrations (1.4.3)
       activerecord (>= 5.2)
+    terminal-table (3.0.2)
+      unicode-display_width (>= 1.1.1, < 3)
     terser (1.1.14)
       execjs (>= 0.3.0, < 3)
     thor (1.2.1)
@@ -552,6 +566,7 @@ DEPENDENCIES
   htmlentities
   http_accept_language (~> 2.1.1)
   i18n-js (~> 3.9.2)
+  i18n-tasks
   image_optim_rails
   image_processing
   jbuilder (~> 2.7)

config/i18n-tasks.yml

@@ -0,0 +1,160 @@
+# i18n-tasks finds and manages missing and unused translations: https://github.com/glebm/i18n-tasks
+
+# The "main" locale.
+base_locale: en
+## All available locales are inferred from the data by default. Alternatively, specify them explicitly:
+# locales: [es, fr]
+## Reporting locale, default: en. Available: en, ru.
+# internal_locale: en
+
+# Read and write translations.
+data:
+  ## Translations are read from the file system. Supported format: YAML, JSON.
+  ## Provide a custom adapter:
+  # adapter: I18n::Tasks::Data::FileSystem
+
+  # Locale files or `File.find` patterns where translations are read from:
+  read:
+    ## Default:
+    - config/locales/en.yml
+    ## More files:
+    # - config/locales/**/*.%{locale}.yml
+
+  # Locale files to write new keys to, based on a list of key pattern => file rules. Matched from top to bottom:
+  # `i18n-tasks normalize -p` will force move the keys according to these rules
+  write:
+    ## For example, write devise and simple form keys to their respective files:
+    # - ['{devise, simple_form}.*', 'config/locales/\1.%{locale}.yml']
+    ## Catch-all default:
+    # - config/locales/%{locale}.yml
+
+  # External locale data (e.g. gems).
+  # This data is not considered unused and is never written to.
+  external:
+    ## Example (replace %#= with %=):
+    # - "<%#= %x[bundle info vagrant --path].chomp %>/templates/locales/%{locale}.yml"
+
+  ## Specify the router (see Readme for details). Valid values: conservative_router, pattern_router, or a custom class.
+  # router: conservative_router
+
+  yaml:
+    write:
+      # do not wrap lines at 80 characters
+      line_width: -1
+
+  ## Pretty-print JSON:
+  # json:
+  #   write:
+  #     indent: '  '
+  #     space: ' '
+  #     object_nl: "\n"
+  #     array_nl: "\n"
+
+# Find translate calls
+search:
+  ## Paths or `File.find` patterns to search in:
+  # paths:
+  #  - app/
+
+  ## Root directories for relative keys resolution.
+  # relative_roots:
+  #   - app/controllers
+  #   - app/helpers
+  #   - app/mailers
+  #   - app/presenters
+  #   - app/views
+
+  ## Directories where method names which should not be part of a relative key resolution.
+  # By default, if a relative translation is used inside a method, the name of the method will be considered part of the resolved key.
+  # Directories listed here will not consider the name of the method part of the resolved key
+  #
+  # relative_exclude_method_name_paths:
+  #  -
+
+  ## Files or `File.fnmatch` patterns to exclude from search. Some files are always excluded regardless of this setting:
+  ##   *.jpg *.jpeg *.png *.gif *.svg *.ico *.eot *.otf *.ttf *.woff *.woff2 *.pdf *.css *.sass *.scss *.less
+  ##   *.yml *.json *.zip *.tar.gz *.swf *.flv *.mp3 *.wav *.flac *.webm *.mp4 *.ogg *.opus *.webp *.map *.xlsx
+  exclude:
+    - app/assets/images
+    - app/assets/fonts
+    - app/assets/videos
+    - app/assets/builds
+
+  ## Alternatively, the only files or `File.fnmatch patterns` to search in `paths`:
+  ## If specified, this settings takes priority over `exclude`, but `exclude` still applies.
+  # only: ["*.rb", "*.html.slim"]
+
+  ## If `strict` is `false`, guess usages such as t("categories.#{category}.title"). The default is `true`.
+  strict: false
+
+  ## Allows adding ast_matchers for finding translations using the AST-scanners
+  ## The available matchers are:
+  ## - RailsModelMatcher
+  ##     Matches ActiveRecord translations like
+  ##     User.human_attribute_name(:email) and User.model_name.human
+  ##
+  ## To implement your own, please see `I18n::Tasks::Scanners::AstMatchers::BaseMatcher`.
+  <%# I18n::Tasks.add_ast_matcher('I18n::Tasks::Scanners::AstMatchers::RailsModelMatcher') %>
+
+  ## Multiple scanners can be used. Their results are merged.
+  ## The options specified above are passed down to each scanner. Per-scanner options can be specified as well.
+  ## See this example of a custom scanner: https://github.com/glebm/i18n-tasks/wiki/A-custom-scanner-example
+
+## Translation Services
+# translation:
+#   # Google Translate
+#   # Get an API key and set billing info at https://code.google.com/apis/console to use Google Translate
+#   google_translate_api_key: "AbC-dEf5"
+#   # DeepL Pro Translate
+#   # Get an API key and subscription at https://www.deepl.com/pro to use DeepL Pro
+#   deepl_api_key: "48E92789-57A3-466A-9959-1A1A1A1A1A1A"
+#   # deepl_host: "https://api.deepl.com"
+#   # deepl_version: "v2"
+
+## Do not consider these keys missing:
+# ignore_missing:
+# - 'errors.messages.{accepted,blank,invalid,too_short,too_long}'
+# - '{devise,simple_form}.*'
+
+## Consider these keys used:
+ignore_unused:
+  - 'geocoder.search_osm_nominatim.prefix.*'
+  - 'javascripts.*'
+  - 'activerecord.attributes.*'
+  - 'activerecord.models.*'
+  - 'activerecord.help.*'
+  - 'helpers.submit.*'
+  - 'datetime.distance_in_words_ago.*'
+  - 'reports.new.categories.*' # double interpolation in reports_helper
+# - '{devise,kaminari,will_paginate}.*'
+# - 'simple_form.{yes,no}'
+# - 'simple_form.{placeholders,hints,labels}.*'
+# - 'simple_form.{error_notification,required}.:'
+
+## Exclude these keys from the `i18n-tasks eq-base' report:
+# ignore_eq_base:
+#   all:
+#     - common.ok
+#   fr,es:
+#     - common.brand
+
+## Exclude these keys from the `i18n-tasks check-consistent-interpolations` report:
+# ignore_inconsistent_interpolations:
+# - 'activerecord.attributes.*'
+
+## Ignore these keys completely:
+# ignore:
+#  - kaminari.*
+
+## Sometimes, it isn't possible for i18n-tasks to match the key correctly,
+## e.g. in case of a relative key defined in a helper method.
+## In these cases you can use the built-in PatternMapper to map patterns to keys, e.g.:
+#
+# <%# I18n::Tasks.add_scanner 'I18n::Tasks::Scanners::PatternMapper',
+#       only: %w(*.html.haml *.html.slim),
+#       patterns: [['= title\b', '.page_title']] %>
+#
+# The PatternMapper can also match key literals via a special %{key} interpolation, e.g.:
+#
+# <%# I18n::Tasks.add_scanner 'I18n::Tasks::Scanners::PatternMapper',
+#       patterns: [['\bSpree\.t[( ]\s*%{key}', 'spree.%{key}']] %>