feat(workspaceobject): Add workspace object controller

[MisterMX]

Summary

This PR introduces a new API, WorkspaceObject, which enables managing any Kubernetes object within a workspace. The controller uses a RootShard reference and the workspace path to construct the appropriate kubeconfig. The API design is inspired by the Object API from https://github.com/crossplane-contrib/provider-kubernetes and includes a spec.managementPolicies field to control which operations (create, update, delete) the controller should perform.

The goal of this PR is to address #122. Instead of supporting only a single kind, we adopt a broader, more generic approach that supports any object type, including Workspace, WorkspaceType, and RBAC configurations.

This work aims to provide the following capabilities, enabling us to fully manage a KCP instance without relying on third-party operators that add additional complexity (e.g., Crossplane):

• Manage workspaces and workspace types from the host cluster
• Manage RBAC roles and bindings from the host cluster

At present, the controller does not correctly handle system workspaces, which are shard-local. This may be improved in a future PR to allow administrators to define RBAC configurations in system workspaces for consistent, cluster-wide defaults (e.g., cluster-admin access via OIDC) without needing to apply them per workspace.

on-behalf-of: @eon-se opensource@eon.com

What Type of PR Is This?

/kind feature

Related Issue(s)

Fixes #122

Relates to #91 by providing a way to configure RBAC roles that can be used by generated kubeconfigs.

Release Notes

Add WorkspaceObject API to allow managing any arbitrary object in a workspace.

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