VSA settings: [FE] Migrate adding/editing value streams at the project level to settings page

Proposal

We're moving the VSA value stream configuration / settings at the project level from the modal to a standalone settings page.

• This issue is targeted at moving the existing functionality i.e. screenshots below minus the projects / timespan and labels sections.

Vision

New	Edit

Implementation guide

• Should be behind the vsa_standalone_settings_page feature flag
• Move create value stream functionality to a new page /gitlab-org/gitlab/-/analytics/value_stream_analytics/value_streams/new
  • Update ee/app/views/projects/analytics/cycle_analytics/value_streams/new.html.haml
• Move edit value stream functionality to a new page /gitlab-org/gitlab/-/analytics/value_stream_analytics/value_streams/<value-stream-id>/edit
  • Update ee/app/views/projects/analytics/cycle_analytics/value_streams/edit.html.haml
• Update app/controllers/projects/analytics/cycle_analytics/value_streams_controller.rb
  • Expose value stream data to frontend (see ee/app/controllers/groups/analytics/cycle_analytics/value_streams_controller.rb)
• Create a new entry point at the project level
• Update feature/Jest/QA tests

Additional Notes

• We should be able to re-use the same form for creating and editing
• Create value stream: should redirect to the new/updated value stream on success (/gitlab-org/gitlab/-/analytics/value_stream_analytics/value_streams/<value-stream-id>
• Ignore selected projects, time period and filters fields for now