Move invites spinach test to Rspec

See merge request gitlab-org/gitlab-ce!16126

Move explore groups spinach test to RSpec

See merge request gitlab-org/gitlab-ce!16129

Resolve "Improve non-triggered manual action job detail page"

Closes #22643 and #37843

See merge request gitlab-org/gitlab-ce!15991

When a project uses fast-forward merging strategy user has
to rebase MRs to target branch before it can be merged.
Now user can do rebase in UI by clicking 'Rebase' button
instead of doing rebase locally.

This feature was already present in EE, this is only backport
of the feature to CE. Couple of changes:
* removed rebase license check
* renamed migration (changed timestamp)

Closes #40301

* master: (200 commits)
  Fix issue boards scroll config.
  Added multi editor setting on the profile preferences page
  fix missing import of timeWeek which would cause errors in prometheus graphs with deployments
  Remove downcase from special path helper
  Rename db:seed_fu-{pg,mysql} to gitlab:setup-{pg,mysql}
  Fix error when viewing diffs without blobs
  Moves prettier to dev dependency
  Eager load event target authors whenever possible
  Do not run ee_compat_check on security branches
  Include integration tests in CE/EE testing documentation
  41054-Disallow creation of new Kubernetes integrations
  Resolve "Resizable file list and commit panel"
  Make tooltip placement bottom by default as per design guidelines
  Fix groups list icon, timestamp alignment and row height
  Avoid leaving a push event empty if payload cannot be created
  Move git operations for UpdateRemoteMirrorService into Gitlab::Git
  Move delete_remote_branches from Gitlab::Shell to Gitlab::Git::Repository
  Move push_remote_branches from Gitlab::Shell to Gitlab::Git::Repository
  Update Kubernetes service documentation
  fix issue #37843
  ...