Deployment Tracing feature for better link between CI & CD

[khanhtc1202]

What would you like to be added:

We want a better way to link CI and CD (using PipeCD). The current PipeCD working context focuses mostly on manifest repo. Users need a way to actually understand which change in the source code repo triggers which deployment(s).

Why is this needed:

By introducing Event Context (ref: #5295), users now can have a link from deployment to the code changed by visiting the manifest changed commit, with the information provided to PipeCD via pipectl event register command. But it's just one way, from the CD to the CI, for tracking back; it would be better to have a way from CI to CD when devs (who change the source code) know the source code commit and want to find the change reflected deployment(s).