Add support for translatable/readonly for uploaded/downloaded Android Resource Format

[harriebird]

Proposed changes

This adds readonly/translatable support for Android Resource format. Prior to this change, the translatable tag in the uploaded Android Resource file is ignored in the web UI and it is not added when downloading the file. With this, translatable="false" adds a readonly state. The said tag is kept even in the downloaded file. The dependency translate-toolkit minimum version was set to 3.13.4 to utilize those changes related to this.
This solves issue #4902.

Checklist

• Lint and unit tests pass locally with my changes.
• I have added tests that prove my fix is effective or that my feature works.
• I have added documentation to describe my feature.
• I have squashed my commits into logic units.
• I have described the changes in the commit messages.

Other information

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.15%. Comparing base (cb14410) to head (118fd7c).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #12697      +/-   ##
==========================================
- Coverage   91.19%   91.15%   -0.04%     
==========================================
  Files         596      596              
  Lines       61071    61091      +20     
  Branches     6340     6341       +1     
==========================================
- Hits        55695    55690       -5     
- Misses       3728     3753      +25     
  Partials     1648     1648              

Files with missing lines	Coverage Δ
weblate/formats/ttkit.py	91.45% <100.00%> (+0.03%)	⬆️
weblate/trans/models/translation.py	86.10% <ø> (ø)
weblate/trans/tests/test_files.py	100.00% <100.00%> (ø)

... and 3 files with indirect coverage changes