[JENKINS-49138] Build Now to redirect to new build

[jglick]

See JENKINS-49138. There are a lot of different UI gestures to trigger a build, and this just covers one of them so far, and perhaps not in the ideal way (needs UX design in some cases). Not sure if I have the appetite to continue, or if it makes sense to open for review even when incomplete.

• [X] Build Now from sidebar of project redirects to new build
• [ ] warn user if build is not scheduled immediately (mainly relevant for non-Pipeline projects)
• [ ] Build Now in context menu
• [ ] Build column button
• [ ] Build with Parameters form submission
• [ ] Pipeline Replay / Rebuild
• [ ] Declarative Pipeline Restart from Stage (https://github.com/jenkinsci/pipeline-model-definition-plugin/pull/228#discussion_r183927485)

Testing done

https://user-images.githubusercontent.com/154109/217349251-013a84cf-481e-406b-830b-da46024fe31d.mp4

Proposed changelog entries

• TBD

Maintainer checklist

Before the changes are marked as ready-for-merge:

• [ ] There are at least two (2) approvals for the pull request and no outstanding requests for change.
• [ ] Conversations in the pull request are over, or it is explicit that a reviewer is not blocking the change.
• [ ] Changelog entries in the pull request title and/or Proposed changelog entries are accurate, human-readable, and in the imperative mood.
• [ ] Proper changelog labels are set so that the changelog can be generated automatically.
• [ ] If the change needs additional upgrade steps from users, the upgrade-guide-needed label is set and there is a Proposed upgrade guidelines section in the pull request title (see example).
• [ ] If it would make sense to backport the change to LTS, a Jira issue must exist, be a Bug or Improvement, and be labeled as lts-candidate to be considered (see query).

[github-actions[bot]]

Please take a moment and address the merge conflicts of your pull request. Thanks!

[jglick]

Ideally would wait for #7635.

[jglick]

This is now actionable again, back to my to-do list…