ci: add codeql config

[corneliusroemer]

Adds CodeQL config, which automatically scans for security vulnerabilities.

Python and Typescript work without custom config, but kotlin required some.

[github-advanced-security]

This pull request sets up GitHub code scanning for this repository. Once the scans have completed and the checks have passed, the analysis results for this pull request branch will appear on this overview. Once you merge this pull request, the 'Security' tab will show more code scanning analysis results (for example, for the default branch). Depending on your configuration and choice of analysis tool, future pull requests will be annotated with code scanning analysis results. For more information about GitHub code scanning, check out the documentation.

[anna-parker]

@corneliusroemer I see this error when I look into the security section on github:
- will this PR fix this or is github/codeql-action#2378 (comment) potentially still causing issues?

[theosanderson]

Seems useful!

[corneliusroemer]

Great question @anna-parker - I should have been explicit.

1. I set up codeql with default settings (no config file)
2. This ran, it worked for Python and TS, it failed for kotlin
3. This is the notification you see, that something failed
4. I then switched to advanced config (having explicit config file)
5. This is the PR here
6. Based on how codeql works, the advanced config doesn't make the warning disappear until it's merged into main
7. The codeql config here ran on this branch and it worked, so it shouldn't error again.

Hope this makes sense!