feat: add CORS to operations API

[davidgamez]

Summary:

Add CORS to the operations API.

Expected behavior:

A request with a preflight header is allowed.

Testing tips:

After deployment in DEV, this request must pass:

curl -i -X OPTIONS \
  "https://{dev-api-address}/operations-api/v1/operations/feeds?offset=0&limit=50" \
  -H "Origin: https://mobilitydatabase-operations-qmih98m11-mobility-data.vercel.app" \
  -H "Access-Control-Request-Method: GET" \
  -H "Access-Control-Request-Headers: authorization,content-type"

Please make sure these boxes are checked before submitting your pull request - thanks!

• Run the unit tests with ./scripts/api-tests.sh to make sure you didn't break anything
• Add or update any needed documentation to the repo
• Format the title like "feat: [new feature short description]". Title must follow the Conventional Commit Specification(https://www.conventionalcommits.org/en/v1.0.0/).
• Linked all relevant issues
• Include screenshot(s) showing how this pull request works and fixes the issue(s)