Add Git Detail

[timja]

Adds a commit link to the build page with experimental UI - relates to jenkinsci/github-branch-source-plugin#826

Testing done

Enabled experimental flag for build redesign on latest weekly.
Setup two pipelines with a pipeline hosted on GitHub.
One using GitHub SCM and one with GitSCM.

GitSCM now has a commit detail whereas before it had nothing.
GitHub branch jobs have a duplicate detail as github-branch-source is adding GitSCM details but that can be removed
GitHub Pull request jobs don't have a duplicate as the pull request scm fails an instanceof check and the git plugin doesn't add another details entry

Untested but non github based jobs should either have no link, or use the configured repository browser / the plugin will use the pre-existing guess method too

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I can add some integration tests but want to check the direction so far

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests that demonstrate the feature works or the issue is fixed

[timja]

I'm not sure about this, I couldn't find any way to get to the Repository Browser from a SCMSource.

The existing getBrowser() in this class just returns null.
Javadoc says it should then fallback to the auto browser, which seems to no longer exist / is disabled by default.

I've copied the guess implementation from GitSCM as I can't see a way to go from a SCMSource to an SCM.

WorkflowRun does have a getSCMs method and its possible to get there that way.

[timja]

I've got more tests locally but really struggling to get the right APIs =/
Will see how I get on