Create Project Security Settings API

What does this MR do and why?

Creates a new API that allows authenticated users to modify and view their project security settings. Specifically this only allows modifying pre_receive_secret_detection_enabled for the time being as the other fields have bigger impact than the scope of this change. Also added are some spec tests and documentation on how to use the API with examples.

resolves #490359 (closed)

References

Please include cross links to any resources that are relevant to this MR This will give reviewers and future readers helpful context to give an efficient review of the changes introduced.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.