Support CORS headers for cross site requests

[MrCreosote]

Hardcoding allowed sites for now

[dauglyon]

LGTM, as discussed adding this to the config is probably a good future move.

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 53.38%. Comparing base (880e9fc) to head (d8d7d73).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
cdmtaskservice/app.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #542      +/-   ##
==========================================
- Coverage   53.38%   53.38%   -0.01%     
==========================================
  Files          69       69              
  Lines        5895     5897       +2     
==========================================
+ Hits         3147     3148       +1     
- Misses       2748     2749       +1     

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