use random uuid suffix in cover image key with size validation

[sainak]

Proposed Changes

• use random uuid suffix in cover image key
• add validator to only allow jpg and png images
• add image resolution and size validator for cover image uploads
• closes Change backend logic for setting the cover image key #2469

Merge Checklist

• Tests added/fixed
• Update docs in /docs
• Linting Complete
• Any other necessary step

Only PR's with test cases included and passing lint and test pipelines will be reviewed

@ohcnetwork/care-backend-maintainers @ohcnetwork/care-backend-admins

[codecov]

Codecov Report

Attention: Patch coverage is 40.38462% with 31 lines in your changes missing coverage. Please review.

Project coverage is 64.82%. Comparing base (8513421) to head (d73dee2).
Report is 1 commits behind head on develop.

Files with missing lines	Patch %	Lines
care/utils/models/validators.py	40.00%	27 Missing ⚠️
care/facility/api/serializers/facility.py	42.85%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2472      +/-   ##
===========================================
- Coverage    64.90%   64.82%   -0.09%     
===========================================
  Files          242      242              
  Lines        13809    13858      +49     
  Branches      1906     1920      +14     
===========================================
+ Hits          8963     8983      +20     
- Misses        4468     4497      +29     
  Partials       378      378              

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