Merge CSI plugin code.

[blackpiglet]

Thank you for contributing to Velero!

Please add a summary of your change

This PR contains many file changes.
To reduce the reviewers' burden, highlight the main change here:

• Replace the external-snapshotter client and the k8s native client with the controller-runtime client.
• Modify how the plugins are registered.
• Refactor some functions.

P.S. Reviewers can ignore the change under the directory github.com/vmware-tanzu/velero/pkg/restore/actions because correcting the files' package name is the only change.

Does your change fix a particular issue?

Fixes #7408

Please indicate you've done the following:

• Accepted the DCO. Commits without the DCO will delay acceptance.
• Created a changelog file or added /kind changelog-not-required as a comment on this pull request.
• Updated the corresponding documentation in site/content/docs/main.

[codecov]

Codecov Report

Attention: Patch coverage is 53.43811% with 711 lines in your changes are missing coverage. Please review.

Project coverage is 61.72%. Comparing base (b91b907) to head (8df4e6a).

Files	Patch %	Lines
pkg/backup/actions/csi/volumesnapshot_action.go	0.00%	175 Missing ⚠️
pkg/backup/actions/csi/pvc_action.go	64.45%	90 Missing and 28 partials ⚠️
pkg/restore/actions/csi/volumesnapshot_action.go	3.29%	88 Missing ⚠️
pkg/util/csi/volume_snapshot.go	74.39%	74 Missing and 11 partials ⚠️
pkg/restore/actions/csi/pvc_action.go	80.16%	50 Missing and 20 partials ⚠️
...backup/actions/csi/volumesnapshotcontent_action.go	0.00%	48 Missing ⚠️
...estore/actions/csi/volumesnapshotcontent_action.go	0.00%	40 Missing ⚠️
...g/backup/actions/csi/volumesnapshotclass_action.go	0.00%	38 Missing ⚠️
.../restore/actions/csi/volumesnapshotclass_action.go	0.00%	38 Missing ⚠️
pkg/util/podvolume/pod_volume.go	81.81%	3 Missing and 3 partials ⚠️
... and 2 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7609      +/-   ##
==========================================
- Coverage   61.90%   61.72%   -0.18%     
==========================================
  Files         266      276      +10     
  Lines       29467    24709    -4758     
==========================================
- Hits        18241    15252    -2989     
+ Misses       9934     8101    -1833     
- Partials     1292     1356      +64     

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[reasonerjt]

There are many RIA moved into restore/actions but only CSI related BIA into bakcup/actions.

For the first step, I wish to suggest put all CSI plugins into backup/csi or just into backup package and name the file explicitly like csi_xxxx.go

[blackpiglet]

There are many RIA moved into restore/actions but only CSI related BIA into bakcup/actions.

For the first step, I wish to suggest put all CSI plugins into backup/csi or just into backup package and name the file explicitly like csi_xxxx.go

Backup-related actions are already put into the github.com/vmware-tanzu/velero/pkg/backup/actions/ in the previous PR.
This PR modifies the restore-related actions because the package names were not set correctly.