Add support for Multiple VolumeSnapshotClasses

[anshulahuja98]

Fix: #5750

Design: vmware-tanzu/velero#5774

[Shashank1306s]

Added comments in internal/util/util.go

[blackpiglet]

Looks like VolumeSnapshotClassDriverBackupAnnotationPrefix and is duplicated with VolumeSnapshotClassDriverPVCAnnotation.

[anshulahuja98]

Actually all 3 variables including VolumeSnapshotClassSelectorLabel have the same string
I kept that intentionally same to make user experience easier
While on the other hand - all are separate 3 variables such that it is easy to change in code than reusing the variables.

Do you have any suggestion for keeping the values different?

[sseago]

I agree that these are logically different parameters. I think it's fine that they have the same value, since they're used in different contexts -- i.e. a PVC annotation shouldn't need to be called "csi-volumesnapshot-class-pvc" since it's already on the PVC.

[anshulahuja98]

CC @shubham-pampattiwar for review

[sseago]

Added some comments. We can't merge this until we get the design PR approved and merged, though.

[sseago]

I agree that these are logically different parameters. I think it's fine that they have the same value, since they're used in different contexts -- i.e. a PVC annotation shouldn't need to be called "csi-volumesnapshot-class-pvc" since it's already on the PVC.

[anshulahuja98]

Added some comments. We can't merge this until we get the design PR approved and merged, though.

Resolved all comments and merge conflicts
@sseago Can you please request someone from the maintainers team to review this PR/ approve design PR.
At this point I have requested too many times in the community meetings without receiving traction

[shubham-pampattiwar]

Lets get the design merged in first.

[anshulahuja98]

The design PR has been approved by 2 maintainers, would be useful if someone can merge it and also meanwhile review/ approve this current PR.

[anshulahuja98]

I am not sure how this got closed, must have done by mistake
@blackpiglet / @sseago / @shubham-pampattiwar can you please approve this.

[anshulahuja98]

Design PR is merged

[anshulahuja98]

@blackpiglet / @shubham-pampattiwar can you please do final signoff and get this merged.

[anshulahuja98]

@reasonerjt can we get this merged as well?