feature: actively manage lifecycle of resource schemas

[embik]

Feature Description

As of now, we do not update APIExports when the service-side CustomResourceDefinition is updated:

api-syncagent/internal/controller/apiresourceschema/controller.go

Lines 141 to 143 in 20aaaa3

	// ARS'es cannot be updated, their entire spec is immutable. For now we do not care about
	// CRDs being updated on the service cluster, but in the future (TODO) we must allow
	// service owners to somehow publish updated CRDs without changing their API version.

To provide necessary lifecycle / day-2 operations for CRDs that evolve within their lifetime, the api-syncagent should be capable of processing changes to the CRDs.

Proposed Solution

The api-syncagent should process CRDs, create new APIResourceSchemas in kcp and update the APIExport to use the new schemas.

Ideally, we also make sure we don't sync up breaking changes, but I have no fleshed out idea what checks should happen in this case.

Alternative Solutions

No response

Want to contribute?

• I would like to work on this issue.

Additional Context

No response