Include --annotations flag in backup and restore create commands

[alromeros]

Thank you for contributing to Velero!

Please add a summary of your change

This Pull Request implements a new --annotations flag in the backup and restore create commands.

This allows users to specify key-value pairs for annotations directly at the time of backup and restore creation, in the same way as the --labels flag.

Usage example:

velero backup create my-backup --include-namespaces default --annotations AnnMetadataBackup=true

For restore:

velero restore create my-restore --include-namespaces default --annotations AnnIgnoreChecks=true

Does your change fix a particular issue?

Fixes #8350

Please indicate you've done the following:

• Accepted the DCO. Commits without the DCO will delay acceptance.
• Created a changelog file (make new-changelog) or comment /kind changelog-not-required on this PR.
• Updated the corresponding documentation in site/content/docs/main.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 58.98%. Comparing base (8320df4) to head (e2839bb).
Report is 8 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #8354   +/-   ##
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  Coverage   58.97%   58.98%           
=======================================
  Files         367      367           
  Lines       38876    38881    +5     
=======================================
+ Hits        22928    22933    +5     
  Misses      14486    14486           
  Partials     1462     1462           

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