Global pipelines list as user homepage

Description

Part of https://gitlab.com/gitlab-org/gitlab-ee/issues/3838.

When dealing with CI/CD-only projects, users may want to have a global pipelines list as their homepage when using GitLab.

Proposal

Add ability to have the global pipelines list after login.

Links / references

Documentation blurb

Overview

What is it? Why should someone use this feature? What is the underlying (business) problem? How do you use this feature?

Use cases

Who is this for? Provide one or more use cases.

Feature checklist

Make sure these are completed before closing the issue, with a link to the relevant commit.

• Feature assurance
• Documentation
• Added to features.yml