Add support to additionally tag an existing OCI manifest

[NotTheEvilOne]

What this PR does / why we need it:
This PR adds support for gl-oci to additionally tag an OCI manifest. It mainly reuses already existing code paths.

Which issue(s) this PR fixes:
Related gardenlinux/gardenlinux#2753

Special notes for your reviewer:
This PR will be tagged 0.9.1.

[codecov]

Codecov Report

❌ Patch coverage is 95.58824% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.95%. Comparing base (0d32884) to head (6d68a09).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/gardenlinux/oci/image_manifest.py	94.18%	5 Missing ⚠️
src/gardenlinux/oci/container.py	97.14%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #176      +/-   ##
==========================================
+ Coverage   90.98%   92.95%   +1.97%     
==========================================
  Files          27       28       +1     
  Lines        1264     1306      +42     
==========================================
+ Hits         1150     1214      +64     
+ Misses        114       92      -22     

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[ByteOtter]

LGTM so far. Just CodeCov complaining about coverage. :)

[yeoldegrove]

I did not completely grasp if adding this breaks our current workflows (if there is a version bump).
Did you already look into this?

Other than that, looks good to me.

[NotTheEvilOne]

I did not completely grasp if adding this breaks our current workflows (if there is a version bump). Did you already look into this?

Other than that, looks good to me.

It's adding a new entrypoint after all so current workflows should not be affected at all.