Add pipeline param to Commit Status API

What does this MR do?

This MR adds a parameter with the wanted pipeline ID, to the Commit Status API. Right now, the API always chooses the latest pipeline for the sha+ref.

The reason we need this, is because we trigger external jobs from the pipeline itself. The external job creates a link, and sends it as a "running" status, so we can monitor the job as it goes (and check results when done). We run the pipeline both on schedule and every commit with different variables that affect the external job, so we can't just always use the "latest" pipeline and assume it is the right one.

What are the relevant issue numbers?

There is no issue. Should I open one?

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer