Support syncing rego rules from Git

[sbernauer]

For some users it might be more convenient to have their rego rules in a Git repo instead of having to put them in ConfigMaps.
For this we could copy the git-sync mechanism in Airflow to OPA servers.

Tasklist

• The first task is to make a decision (ideally as an ADR) if we want to have this functionality at all (e.g. check security aspects or our abstraction layer that we will create)

[fhennig]

@razvan look, you'd be happy about this too! :D

[razvan]

🥰🌈🤗💖🤩