Add more automation workflows

[BlackYps]

Previously we had the problem that sometimes things got merged in develop for testing purposes or that still required more testing when a release came. In any case, sometimes the need arises to revert merged features before doing a release. Checking all the commits is tedious and error-prone.

I created a github project that is supposed to give a nice overview of the status of the current milestone. https://github.com/orgs/FAForever/projects/27/views/2
In this view we can ideally check at a glance if anything needs special attention before doing a release. It also informs us about what is on fafbeta.
At the moment it's actually not useful yet, because all the statuses need to be updated manually which is still error-prone and tedious.
What we want is to automate these things, so we have a reliable status board. We can create github workflows that do exactly this.

You can use the existing workflow to convert pull requests to drafts to see how this generally works. You can use this file as a template. #6460

We can use github cli to manipulate the project. Documentation can be found here:
https://cli.github.com/manual/
https://docs.github.com/en/actions/writing-workflows/choosing-when-your-workflow-runs/events-that-trigger-workflows

Automations that we want:
When a PR with area:balance label gets merged, add the needs-testing label
All PRs with needs-testing label should show up in the needs testing category in the project.
All PRs with area:balance label should show up in the area:balance category in the project. (This maybe conflicts with the previous automation, if so we first need to find a smarter way to handle this.)
All PRs with the experimental label should show up in the experimental category in the project.