Address invalid localization files

[jonasraoni]

Describe the bug
Some of our localization files might have an invalid syntax, they might work, due to lax parsers, but also cause unexpected issues with other softwares:

• Weblate might wipe out unrelated content: pkp/ops@cc6187b
• The gettext package might ignore the text: Handling of defective .po files php-gettext/Gettext#282

Besides that, as the localization is also maintained by non-technical people, it makes sense to ensure some things are not broken on the way.

Solution

• Require the review of changes made to the default locale (e.g. user changed a translation and removed a variable) at Weblate (or review them carefully when integrating updates)
• Write a validation tool
• Integrate the tool into the GitHub Actions to validate the plugins/applications
• Consider ideas from Tool to detect unused locale keys #7978
• Consider ideas from pkp/ojs@baf1ce4
• Validate syntax of .po files
• Validate variables
  • Variables from the default locale should be present on the other locales
  • The variable name should be in camel case
  • Unexpected extra variables on the side locales can be flagged during build time
• During build time, the Locale class might also flag variables which were passed to it, but not used/replaced (something might be missing)

The tool can be written for stable-3_3_0, as it's not a breaking change.

What application are you using?
OJS/main

[jonasraoni]

@asmecher I've created a PR for the pkp-lib/main here:

• Bugfix/main/8081 fix invalid locales #8094

I've added a generic validator for the locale files, and most of the fixes are to satisfy the requirements and warnings of the msgfmt validator.

I've tried to isolate the commits, except the 4f379aa... There I used the gettext package to setup the plurals, and it also formatted and removed duplicated entries (inside the same file).

If everything sounds fine, I'll update the other branches.

p.s.: I'm able to reduce the line-break noise by doing a small change to the gettext package.

[jonasraoni]

For the stable-3_3_0, I can pass my modified validator through the locale files, and fix the breaking issues.

I also think it's ok to add the validate-locale.sh in a non-breaking way (e.g. emit errors without failing the build)

[asmecher]

Please hold off on this until we've reached a decision about translation workflows on this discussion: #8038

[jonasraoni]

Ok! So I'll just commit fixes for the broken keys (e.g. missing quotes, bad escaping, ...).

[asmecher]

Yes please -- I've recently merged translations from Weblate so now is a good time.

[jonasraoni]

Just to confirm, I've updated the broken files.

[jonasraoni]

@asmecher I've reviewed and moved the fixes related to duplicated keys here #8119

Also, I fixed the syntax errors on stable-3_3_0.