FE: Add a “Pending promotion” tab to the group and project, list the pending promotions there

We need to add Pending Promotion tab to display promotion request lists at Group and Project membership management pages (e.g. http://127.0.0.1:3000/groups/gitlab-org/-/group_members and http://127.0.0.1:3000/h5bp/html5-boilerplate/-/project_members).

Relevant BE issue to integrate with: #433173 (closed)

UI should match that in other tabs. Filtering and sorting is a nice-to-have at this stage.

This very page will later be used to display All SaaS pending promotions.

Draft UI: image

Draft MR for integration PoC: !147249 (closed)

Draft implementation plan:

MR status
Custom Component for the tab workflowcomplete
Custom store or Apollo store workflowcomplete
Pagination workflowcomplete
Add the table with a proper UI workflowcomplete
Remove the export button workflowcomplete
Post refactoring (defined below) workflowcomplete

Post refactoring issues (might need a separate maintenance issue):

Edited by Ammar Alakkad