Feat: Add Supported languages for campaigns

[abdullai-t]

Summary / Highlights

In this Pull Request, I have made the following key changes:

• New DB models for campaign supported languages
• Added two endpoints for managing supported languages of a campaign

Details (Give details about what this PR accomplishes, include any screenshots etc)

Testing Steps (Provide details on how your changes can be tested)

run make test

Requirements (place an x in each [ ])

• [ ] I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• [ ] I've tested my changes manually.
• [ ] I've added unit tests to my PR.

Transparency (Project board)

• [ ] I've given my PR a meaningful title.
• [ ] I linked this PR to the relevant issue.
• [ ] I moved the linked issue from the "Sprint backlog" to "In progress" when I started this.
• [ ] I moved the linked issue to "QA Verification" now that it is ready to merge.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 22.60870% with 89 lines in your changes missing coverage. Please review.

Project coverage is 55.97%. Comparing base (39ae4e9) to head (b3a8653).

Files	Patch %	Lines
src/api/store/supported_language.py	8.00%	46 Missing :warning:
src/api/handlers/supported_language.py	13.33%	26 Missing :warning:
src/api/services/supported_language.py	12.50%	14 Missing :warning:
src/database/models.py	75.00%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1148 +/- ## ========================================== - Coverage 56.09% 55.97% -0.13% ========================================== Files 461 462 +1 Lines 33928 34042 +114 ========================================== + Hits 19032 19055 +23 - Misses 14896 14987 +91 ```

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