feat(reconciler): Shared reconciliation loop logic for controllers

[abhijith-darshan]

Description

Implements a shared Reconcile functionality that can be adopted by all controllers to have standard base reconciliation loop.

• Handles Adding, Removing common finalizer greenhouse.sap/cleanup and removes the need for individual finalizers for each resource
• Splits the events into EnsureCreated and EnsureDeleted
• Implements standard Deletion condition to check if resource has been deleted to allow garbage collection
• Stores original resource before modification into ctx
• Does a status patch by merging the changes done to the object during reconciliation (Addition / Modification of status fields) from original object (old). This prevents resource generation from changing and can be used in Controller Mgr WithEventFilter to avoid duplicate reconciliation
• Implements default conditions for create state if a specific status func is not passed to Reconcile

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

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

Related Tickets & Documents

• Related to [FEAT] - Standardized reconciliation loop logic for controllers #414

Added tests?

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

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

Added to documentation?

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

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• 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
• 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

[IvoGoman]

This looks good and will make the controllers more readable/ better to maintain, also for new ones.