CLOUDP-334941: Refactored Experimental Connection Secret Controller

[filipcirtog]

Summary

This Pull Request introduces the ConnectionSecret controller as an experimental feature within AKO. The addition will enable us to test the design and functionality on the side before exposing the work to end users. Unit tests are included for the experimental implementation.

Proof of Work

• The controller now watched the AtlasDatabaseUser instead the Secret, allowing us to discard the internal request naming processing (i.e. with $).
• Improved Naming Conventions: Renamed various components for better clarity and understanding.
• Adoption of SSA vs. GET+UPDATE: Introduced Server-Side Apply (SSA) to resource update compared to the previous GET+UPDATE approach.
• ConnectionSecret Updates: Renamed connections secrets, updated labels, and added a new annotation to specify the origin of each connection secret.
• Experimental Mode Introduction: Introduced the feature as experimental, building new resources alongside the existing ones.
• Reversion of Deletions & Legacy Code Isolation: Restored previously deleted components and ensured separation from legacy code.

Checklist

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