Tracking issue for In-place Updates implementation

[sbueringer]

v1.13

Minor:

• @sbueringer Improve InfraMachine controller to only add finalizer after InfraMachine has owner (avoids retries on conflict in RemoveManagedFieldsForLabelsAndAnnotations) (ask @sbueringer for more details, same in CAPV)
• @sbueringer Improve Machine controller unit tests to share more setup and verification code across tests in table tests: ✨ Add in-place updates support for machine controller #12831 (comment)

MHC:

• More advanced MHC behavior (e.g. different behavior during in-place update)
• We should probably find a way to remediate based on Ready & Available Machine condition
• @fabriziopandini Consider if to improve the MS definition of Unhealthy when picking machines for deletion, see 🐛 Fix race conditions ScaleDownOldMS #12812 (comment)

Currently not planned for v1.13

Support for multiple extensions:

• Includes: Hook ordering
  • Note: It’s important that hooks of different update extensions are called in the same order for CanUpdateMachine/CanUpdateMachineSet and UpdateMachine hooks
• Improve how to configure to which “objects” a RuntimeExtension applies
  • Goal: We should avoid unnecessary CanUpdateMachine/MachineSet calls (e.g. for the wrong infra provider)
  • Ideas: ExtensionConfig objectSelector (like FieldSelectorRequirement), Extend response of Discovery call (e.g. objectSelector (like FieldSelectorRequirement) or “infraProviderKind”)

Misc:

• KCP: Optimize preflightCheck calls: ✨ KCP: Implement CanUpdateMachine #12857 (comment)
  • KCP should not spam "Rolling out Control Plane machines.." while waiting for preflightChecks to pass
• Improve ExtensionConfig pause behavior: updating the registry is also paused, warmup runnable ignores pause today, alternatively: stop supporting pause