feat: Add Crowdin integration for localization.

[Kiran-B]

Progress / Closed on issue #
#135

What it Does

• Add Crowdin integration for localization.
• Create GH action workflow that pushes the latest strings file to Crowdin. It then pulls the latest assets and generates a PR.
• Also, restructure German as a sublanguage in the group.

How I Tested

• Momentarily set the GH workflow to trigger the action for push from branch: feature/135-add-additional-localizations. This can be verified here: https://github.com/Kiran-B/brain-marks/actions/runs/3182620808/workflow
• It successfully executed the workflow. This can be verified here: https://github.com/Kiran-B/brain-marks/actions/runs/3182620808/jobs/5188799588
• The action successfully created a PR. This used a sample Crowdin Project that I had setup. PR: chore: New Crowdin translations to review and merge Kiran-B/brain-marks#2

Notes

Two important setups are required to be done by this repo owner before this PR can be merged:

1. Create a Crowdin Project with the required languages chosen.
2. Define two secrets in this repo setting. CROWDIN_PROJECT_ID & CROWDIN_PERSONAL_TOKEN.

Screenshot

Restructure of German Localizable.strings as a sublanguage in the group:
Before:

After:

[mikaelacaron]

@Kiran-B thanks for the work! I want to hold off on this until after Hacktoberfest, because of the project changes that are required. (I don't have the time at the moment)

You're welcome to work on another issue!