Design: When :needs connection refers to a stage, show it in the pipeline graph

Release notes

Problem to solve

In #220758 we're working on making it possible for :needs to refer to a stage. we need to make sure we accurately show such dependency in the visualization.

Intended users

User experience goal

When using :needs to refer to a stage I want to see those connections in the pipeline visualization.

Proposal

As per #232946 (closed) when a job needs all jobs in a specific stage, when you hover over that job we'll highlight all the jobs it's dependent on. It shouldn't matter if the :needs relationship was established to individual jobs or to a stage (as a collection of jobs). We show the connections to all individual jobs that a job needs when you hover over that job.

Further details

This is the design issue to address the UI changes necessary for #220758

Permissions and Security

Documentation

Availability & Testing

What does success look like, and how can we measure that?

What is the type of buyer?

Is this a cross-stage feature?

Links / references