feat: add fish completion for yarn workspaces

modules/home-manager/fish/yarn.nix

@@ -0,0 +1,27 @@
+{}:
+
+{
+  xdg.configFile.fishCompletionYarn = {
+    executable = true;
+    target = "fish/completions/yarn.fish";
+    text = ''
+      function __fish_yarn_get_workspaces
+        if type -q jq && test -f package.json
+          command \
+            # List all workspaces glob patterns in the current workspaces
+            jq -r '.workspaces | .[]' package.json 2>/dev/null |\
+            # list nested package.json files in every glob pattern
+            xargs -I {} -- fish -c "ls {}/package.json 2>/dev/null" |\
+            # get name of the workspace from the package.json
+            xargs -I {} -- fish -c "jq -r '.name' {} 2>/dev/null" |\
+            # remove empty lines
+            grep -v '^$' 2>/dev/null |\
+            # remove duplicates
+            sort -u 2>/dev/null
+        end
+      end
+
+      complete -f -c yarn -n '__fish_seen_subcommand_from workspace' -a "(__fish_yarn_get_workspaces)"
+    '';
+  };
+}