Revert Create Project Level Constants and Implement frontend/scripts Constants File

🗣 Description

Remove project level ./constants.ts. Add frontend/scripts/constants.ts to maintain code deduplication across api.js and docs.js. Revert cors options found in backend/src/app.ts to use hard-coded values.

💭 Motivation and context

In PR #2484, I implemented a project-level constants file for storing cors options to reduce duplication of code. This causes issues with deployment and tests. More specifically, the backend configuration doesn't allow importing files/constants from outside the backend directory.

🧪 Testing

Backend Pipeline runs successfully as seen here.

✅ Pre-approval checklist

[x] This PR has an informative and human-readable title.
[x] Changes are limited to a single goal - eschew scope creep!
[x] All future TODOs are captured in issues, which are referenced in code comments.
[x] All relevant type-of-change labels have been added.
[x] I have read the CONTRIBUTING document.
[x] These code changes follow cisagov code standards.
[x] All relevant repo and/or project documentation has been updated to reflect the changes in this PR.
[x] Tests have been added and/or modified to cover the changes in this PR.
[x] All new and existing tests pass.

✅ Pre-merge checklist

[ ] Revert dependencies to default branches.
[ ] Finalize version.

✅ Post-merge checklist

[ ] Create a release.

cisagov / crossfeed