added machineclasses CRD for out-of-tree machine controllers

[MartinWeindel]

How to categorize this PR?

/area control-plane
/kind enhancement
/priority normal

What this PR does / why we need it:
The CRD of the generic machineclass used by all out-of-tree machine controllers is added to the well-known list of machine CRDs. This avoids that every infrastructure provider using OOT MCM has to deploy it explicitly.

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Release note:

added machineclasses CRD for out-of-tree machine controllers

[MartinWeindel]

cc @prashanth26

[prashanth26]

Hi @MartinWeindel ,

Thanks for the quick change. Also this might not be needed right? - https://github.com/gardener/gardener/blob/f12bb20a834bd14221f8d9a8f36dd70de7d2aa47/extensions/pkg/controller/worker/machine_crds.go#L196-L333. If it's not required, we could remove this as well?

[MartinWeindel]

Hi @MartinWeindel ,

Thanks for the quick change. Also this might not be needed right? -

https://github.com/gardener/gardener/blob/f12bb20a834bd14221f8d9a8f36dd70de7d2aa47/extensions/pkg/controller/worker/machine_crds.go#L196-L333

. If it's not required, we could remove this as well?

Wouldn't it be better to keep the old machine classes as long as there are still providers with in-tree machine controllers?

[rfranzke]

/invite @prashanth26 @hardikdr

[prashanth26]

Wouldn't it be better to keep the old machine classes as long as there are still providers with in-tree machine controllers?

Sorry, you are right. I mistook this change to be on the provider-vSphere repo, it's actually on the gardener/extensions. Yes, this old code should exist here. Probably in future, we can get rid of the old machine classes once migrations are done.

[rfranzke]

/lgtm

[hardikdr]

Looks good. Thanks.

[MartinWeindel]

updated description text for provider field as suggested by @prashanth26

[prashanth26]

/lgtm