Improve validation error messages (including oneOf)

[Bjwebb]

No description provided.

[odscjames]

This might be a dupe of a ticket in the BODS CRM?

[Bjwebb]

There's definitely an internal plan.io issue https://opendataservices.plan.io/issues/19384.
I deliberately created an extra public issue, to link my public commits against. Does this make sense?

[Bjwebb]

Dev deploy: http://16-oneof-validation.cove.cove-dev-bods.default.opendataservices.uk0.bigv.io
And here's a sample file to test with: https://raw.githubusercontent.com/openownership/lib-cove-bods/104b79a38a3fa4a82581c1059aee5023ada98090/tests/fixtures/api/basic_statement_id_and_type_errors.json

Instead of

We now have

[kd-ods]

[Related issue now on the BODS agile board: http://bods.opendataservices.coop/redmine/issues/436]

[kd-ods]

Minor text improvement suggestion: instead of "'xxxx' is too short", have "'statementID 'xxxx' is too short"

(If we try to get a field name into all Error Descriptions, users can glance down the Error Description column and see in a one-er which fields are causing problems.)

[Bjwebb]

This issue has had the work on theming and rewording validation errors added to it.
See this google doc for some discussion https://docs.google.com/document/d/1U3e_b-ZaYnx6QEuCSz03Di3lzof7iPDTP8OpSgZyFU8/edit#
The pull requests are the same:

• [WIP] Improve validation error messages OpenDataServices/lib-cove#8
• Improve validation error messages lib-cove-bods#5

Here's a dev instance with a specially crafted file to show all the errors:
http://16-oneof-validation.cove.cove-dev-bods.default.opendataservices.uk0.bigv.io/?source_url=https://raw.githubusercontent.com/openownership/lib-cove-bods/dbb3cd4f4dc1ba08dcf5d3e987decfc02fa57096/tests/fixtures/api/badfile_all_validation_errors.json

[Bjwebb]

I've refactored the work that links to this issues.

I've split out the oneOf work, that has been merged in these two PRs:

• Improve validation error messages for oneOf OpenDataServices/lib-cove#12
• Add tests of improved validation error messages for oneOf lib-cove-bods#8

I've moved the validation message changes into lib-cove-bods, although that requires some changes to lib-cove to put more information into the error JSON.

• Put more data into the error JSON returned, when grouping validation errors OpenDataServices/lib-cove#14
• Improve validation error messages lib-cove-bods#5