Remove ReadySetCyber (RSC) from TypeScript Backend.

[Matthew-Grayson]

Delete TypeORM models for Assessment, Category, Question, Resource, and Response Delete RSC API endpoints
Delete rscSync scan
Delete RSC-related imports in connection.ts, index.ts, and worker.ts Delete mission instance credentials in dev.env.example

🗣 Description

💭 Motivation and context

🧪 Testing

✅ Pre-approval checklist

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

✅ Pre-merge checklist

• Revert dependencies to default branches.
• Finalize version.

✅ Post-merge checklist

• Create a release.

[chrtorres]

LGTM per code review on 11/14/24

[aloftus23]

Looks good to me

[nickviola]

LGTM

[hawkishpolicy]

LGTM.

[jayjaybunce]

Tested functionality across the app and didn't find any impacted functionality.