Add support for CDEvents notifications

[afrittoli]

Comprehensive Summary of your change

Introduce a new notifier format "CDEvents", as described in the CDEvents proposal.

The CDEvents formatter, for now, supports only PUSH_ARTIFACT events.
If other events are selected in the UI, they raise an error in the logs and no event is sent.

The PR is made of two commits:

• add the new notification format to Harbor code
• add the CDEvents option in the format dropdown in the UI

Issue being fixed

Fixes #community/225

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.

[afrittoli]

/label release-note/new-feature

[chlins]

@afrittoli Hi, thanks for your work! Please update to resolve the conflict.

[codecov]

Codecov Report

Merging #18853 (5ffc9bd) into main (b822952) will not change coverage.
Report is 117 commits behind head on main.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main   #18853   +/-   ##
=======================================
  Coverage   44.71%   44.71%           
=======================================
  Files         235      235           
  Lines       13083    13083           
  Branches     2671     2671           
=======================================
  Hits         5850     5850           
- Misses       6938     6939    +1     
+ Partials      295      294    -1     

Flag	Coverage Δ
unittests	44.71% <100.00%> (ø)

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

Files	Coverage Δ
...al/src/app/base/project/webhook/webhook.service.ts	100.00% <100.00%> (ø)

... and 3 files with indirect coverage changes

[chlins]

Yep, I agreed that other event types are not a failure case, user can subscribe other event types from UI but can only receive PUSH events, IMO the better solution is that extend the capability to support limit the event types.

[github-actions]

This PR is being marked stale due to a period of inactivty. If this PR is still relevant, please comment or remove the stale label. Otherwise, this PR will close in 30 days.

[github-actions]

This PR was closed because it has been stalled for 30 days with no activity. If this PR is still relevant, please re-open a new PR against main.

[afrittoli]

I would like to continue working on this - is it an option to re-open? If not I will open a new PR.

[OrlinVasilev]

@afrittoli reopen :) please excuse the automation :D