adopt cosign with oci-spec 1.1

[MinerYang]

Thank you for contributing to Harbor!

Comprehensive Summary of your change

Issue being fixed

Fixes #(issue)

Please indicate you've done the following:

• Well Written Title and Summary of the PR
• Label the PR as needed. "release-note/ignore-for-release, release-note/new-feature, release-note/update, release-note/enhancement, release-note/community, release-note/breaking-change, release-note/docs, release-note/infra, release-note/deprecation"
• Accepted the DCO. Commits without the DCO will delay acceptance.
• Made sure tests are passing and test coverage is added if needed.
• Considered the docs impact and opened a new docs issue or PR with docs changes if needed in website repository.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 67.58%. Comparing base (b7b8847) to head (4f26af6).
Report is 122 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #20245      +/-   ##
==========================================
+ Coverage   67.56%   67.58%   +0.02%     
==========================================
  Files         991     1002      +11     
  Lines      109181   110463    +1282     
  Branches     2719     2781      +62     
==========================================
+ Hits        73768    74660     +892     
- Misses      31449    31789     +340     
- Partials     3964     4014      +50     

Flag	Coverage Δ
unittests	67.58% <0.00%> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
src/server/middleware/cosign/cosign.go	55.40% <ø> (ø)
src/server/middleware/subject/subject.go	47.61% <0.00%> (-0.87%)	⬇️

... and 517 files with indirect coverage changes

[wy65701436]

lgtm