Remove trailing slashes from endpoints, fix check_access for backend roles

[spwoodcock]

What type of PR is this? (check all applicable)

• 🍕 Feature
• 🐛 Bug Fix
• 📝 Documentation
• 🧑‍💻 Refactor
• ✅ Test
• 🤖 Build or CI
• ❓ Other (please specify)

Describe this PR

Trailing slashes, Origin header, and CORS:

• I removed all trailing slashes from routes in FastAPI.
• Proper REST APIs should distinguish between /route/ and /route - they are different.
• We were getting an automatic 307 redirect from FastAPI from /route --> /route/, which was causing the Origin request header to be stripped in Firefox. As a result, with Origin: null the CORS check could not complete, so we get a CORS error.
• I removed this default functionality from FastAPI.
• In future all APIs should not end in a trailing slash. Frontend calls should also account for this.

Fixes check_access logic:

• The logic for check_access on the roles was broken a bit.
• If no org_id was passed, then we need to extract the org_id from the project - fixed this.
• I also updated the project_roles dict to correctly return when user details are returned from the APIs.
• Finally, I converted the project role enum values into numerical values for assessing the hierarchy in check_access.

Checklist before requesting a review

• 📖 Read the FMTM Contributing Guide: https://github.com/hotosm/fmtm/blob/main/CONTRIBUTING.md
• 📖 Read the HOT Code of Conduct: https://docs.hotosm.org/code-of-conduct
• 👷‍♀️ Create small PRs. In most cases, this will be possible.
• ✅ Provide tests for your changes.
• 📝 Use descriptive commit messages.
• 📗 Update any related documentation and include any relevant screenshots.

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