reference integration automation & module PR feedback

Implement [DR-002](https://eclipse-score.github.io/score/main/design_decisions/DR-002-infra.html)

Scope / Acceptance Criteria:
- Continuous Integration
- Hourly continuous integration in reference integration of all modules (main branches)
- On-PR Feedback for individual modules (non blocking!)
- Support Release Branching
- Hourly integration of main branch and release branch - in case there is a difference (e.g. 0.6 branch, which will use `main`, some other branch, latest tag, specific tag of modules - depending on configuration)
- On-PR Feedback for individual modules (non blocking!)

Reminder:
* Include docs build
* This includes documentation, templates, cleanup etc.; Not some hacky proof of concept

NOT in scope (will be reparented once we define the next increment):
* eclipse-score/score#1854