yarn merge-i18n script always unquotes the "title" key

[alanorth]

Describe the bug
The yarn merge-i18n script unquotes the title key, which results in an invalid json5 file (at least according to our eslint rules).

To Reproduce
Steps to reproduce the behavior:

1. Run the yarn merge-i18n script against the default custom theme:

$ yarn merge-i18n -s src/themes/custom/assets/i18n
yarn run v1.22.19
$ ts-node --project ./tsconfig.ts-node.json scripts/merge-i18n-files.ts -s src/themes/custom/assets/i18n
Merging: /home/aorth/src/git/dspace-angular/src/assets/i18n/en.json5 with src/themes/custom/assets/i18n/en.json5
 ████████████████████████████████████████ 100% | ETA: 0s | 100/100
Done in 0.75s.

2. Check the resulting src/assets/i18n/en.json5 and see the title key is unquoted:

diff --git a/src/assets/i18n/en.json5 b/src/assets/i18n/en.json5
index 480bf8834..7ffc7b61a 100644
--- a/src/assets/i18n/en.json5
+++ b/src/assets/i18n/en.json5
@@ -2786,7 +2786,7 @@
 
   "menu.section.browse_community_by_title": "By Title",
 
-  "menu.section.browse_global": "All of DSpace",
+  "menu.section.browse_global": "Browse DSpace",
 
   "menu.section.browse_global_by_author": "By Author",
 
@@ -3464,7 +3464,7 @@
 
   "repository.title": "DSpace Repository",
 
-  "repository.title.prefix": "DSpace Repository :: ",
+  "repository.title.prefix": "DSpace :: ",
 
   "resource-policies.add.button": "Add",
 
@@ -4696,7 +4696,7 @@
 
   "thumbnail.person.placeholder": "No Profile Picture Available",
 
-  "title": "DSpace",
+  title: "DSpace",
 
   "vocabulary-treeview.header": "Hierarchical tree view",
 

Expected behavior
According to our ESLint rules, json5 keys must be quoted, though it doesn't seem this is a requirement from the json5 spec.

This issue might be related: json5/json5#32

[alanorth]

Ah, of course, the json5 library will avoid quoting keys if possible because that is valid in JSON5. The title key is a single word with no special characters that need quoting so json5.stringify is being opportunistic and trying to save us a few bytes.

So the issue here is that our i18n assets are in JSON5 format for human readability, but our current ESLint rules are validating them as JSONC (JSON with comments). This would be partially solved if we switched our ESLint rules to use JSON5 (see #2317).

Having said that, I'm not sure if we actually need our i18n assets to be in JSON5, as it seems we are essentially only using comments, and the Angular frontend is using them in plain JSON format anyway (see src/ngx-translate-loaders/translate-server.loader.ts).