feat(matches): Implement Service Issue-Repository Matches

[dorneanu]

Description

This PR implements #188.

1) The EventRegistry has been changed to use an EventHandler (interface) and EventHandlerFunc (as in net/http). This way we can still On<event name> functions as handlers whenever an event occurs.

2) We added extra logic whenever a new entity is created

• a new Service
  • for each IssueRepository add a default priority
• a new IssueRepository
  • for each Service the default priority will be set

What type of PR is this? (check all applicable)

• [x] 🍕 Feature
• [ ] 🐛 Bug Fix
• [ ] 📝 Documentation Update
• [ ] 🎨 Style
• [x] 🧑‍💻 Code Refactor
• [ ] 🔥 Performance Improvements
• [x] ✅ Test
• [ ] 🤖 Build
• [ ] 🔁 CI
• [ ] 📦 Chore (Release)
• [ ] ⏩ Revert

Related Tickets & Documents

• Related Issue #188

Added tests?

• [x] 👍 yes
• [ ] 🙅 no, because they aren't needed
• [ ] 🙋 no, because I need help
• [ ] Separate ticket for tests # (issue/pr)

Added tests in

• service_handler_test.go
• issue_repository_test.go

Added to documentation?

• [ ] 📜 README.md
• [ ] 🤝 Documentation pages updated
• [x] 🙅 no documentation needed
• [ ] (if applicable) generated OpenAPI docs for CRD changes

Checklist

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my code
• [x] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [ ] New and existing unit tests pass locally with my changes

[MR2011]

The default repository name should also be defined in an environment variable