Add annotation "pv.kubernetes.io/migrated-to" for CSI checking.

[blackpiglet]

1. Also checking annotation "pv.kubernetes.io/migrated-to" to find out whether volume is provisioned by CSI.
2. Add UT test cases.

Signed-off-by: Xun Jiang [email protected]

Thank you for contributing to Velero!

Please add a summary of your change

Does your change fix a particular issue?

Fixes #5149

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-commenter]

Codecov Report

Merging #5181 (7af1e23) into main (701256d) will increase coverage by 0.35%.
The diff coverage is 58.82%.

@@            Coverage Diff             @@
##             main    #5181      +/-   ##
==========================================
+ Coverage   41.25%   41.61%   +0.35%     
==========================================
  Files         212      215       +3     
  Lines       18663    18620      -43     
==========================================
+ Hits         7700     7749      +49     
+ Misses      10389    10294      -95     
- Partials      574      577       +3     

Impacted Files	Coverage Δ
pkg/controller/pod_volume_restore_controller.go	22.85% <0.00%> (+0.73%)	⬆️
pkg/util/kube/utils.go	73.79% <64.28%> (-1.59%)	⬇️
pkg/controller/pod_volume_backup_controller.go	44.06% <100.00%> (+0.39%)	⬆️
pkg/restic/common.go	30.00% <0.00%> (-35.86%)	⬇️
pkg/builder/container_builder.go	33.78% <0.00%> (-4.10%)	⬇️
internal/hook/item_hook_handler.go	87.92% <0.00%> (-1.48%)	⬇️
pkg/controller/restore_controller.go	65.07% <0.00%> (-1.44%)	⬇️
pkg/cmd/server/server.go	6.50% <0.00%> (ø)
pkg/repository/config/config.go	95.91% <0.00%> (ø)
... and 16 more

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[blackpiglet]

Verified with following test cases:

1. backup and restore in same cluster with CSI migration enabled. Pod mounted with in-tree volume.
2. backup and restore in same cluster with CSI migration enabled. Pod mounted with in-tree volume and emptyDir volume.
3. backup and restore in different cluster. backup cluster enabled CSI migration. restore cluster didn't enable CSI migration. Pod mounted with in-tree volume.
4. backup and restore in different cluster. backup cluster didn't enable CSI migration. restore cluster enabled CSI migration. Pod mounted with in-tree volume.