Feature: Scaffold Manager-Worker architecture and KubeSqlWorker CRD

[josephaw1022]

This pull request addresses issue #86 by introducing the scaffolding required for the upcoming Manager-Worker architecture in the KubeSQLServer-Operator.

The primary goal of this initial phase is to establish the new custom resource definition and set up the foundation for the external worker project without disrupting the existing main controller's infrastructure handling.

Key additions in this PR:

• A new KubeSqlWorker CRD model within the operator definitions to act as the central configuration mechanism for worker deployments.
• Scaffolding for a new .NET operator project, ExternalWorker, constructed using the KubeOps SDK templates.
• A foundational testing structure corresponding to the new worker to support future test coverage.
• Integration of these new components into the overarching AppHost and Solution.

The current StatefulSet creation, existing main controller execution logic, and T-SQL components have not been altered, laying the groundwork safely for the external worker architecture.