feat: Add throttle app settings for unauthenticated GIT HTTP requests

- Context: When cloning a git repository via HTTP,
  the command `git clone` always starts with
  an unauthenticated HTTP GET request to the backend before continuing
  with authenticated requests;
  when many `git clone` commands are performaned in parallel
  then these requests are throttled based on the application settings
  e.g. in CI pipelines.

- Add the ability to throttle these unauthenticated GIT HTTP requests
- Add new section to the admin settings page to configure these settings

Changelog: added