11085 bilingual file upload

[gersona]

Proposed changes

A 'Target language" field is added to the Translate document form to identify and process bilingual files

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

fixes #11085

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.14%. Comparing base (b264d2f) to head (fdcee40).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #12713   +/-   ##
=======================================
  Coverage   91.13%   91.14%           
=======================================
  Files         596      596           
  Lines       60966    60979   +13     
  Branches     9648     9651    +3     
=======================================
+ Hits        55564    55579   +15     
+ Misses       3731     3730    -1     
+ Partials     1671     1670    -1     

Files with missing lines	Coverage Δ
weblate/trans/forms.py	89.89% <100.00%> (+<0.01%)	⬆️
weblate/trans/tests/test_create.py	100.00% <100.00%> (ø)
weblate/trans/views/create.py	89.61% <ø> (ø)
weblate/utils/views.py	78.91% <100.00%> (+0.19%)	⬆️

... and 1 file with indirect coverage changes