Parametrize our GH Actions workflow for releasing the 3 operators in a centralized workflow

[mbologna]

Let's use a centralized workflow - this requires refactor of our current GH Actions to release the 3 operators.
For the time being, it will be used just for Highlander (similar to https://github.com/epinio/epinio-end-to-end-tests).
Let's try to create this central workflow under rancher-umbrella org.
When it's working, we can share with Fleet and other teams.

Useful doc: https://docs.github.com/en/actions/using-workflows/reusing-workflows