Having many system notes isn't really an indication of a project being
trending. Including these notes would lead to projects with lots of
commit cross references (for example) showing up in the trending
projects list.

Changes include:

- Ensure Member.add_user is not called directly when not necessary
- New GroupMember.add_users_to_group to have the same abstraction level as for Project
- Refactor Member.add_user to take a source instead of an array of members
- Fix Rubocop offenses
- Always use Project#add_user instead of project.team.add_user
- Factorize users addition as members in Member.add_users_to_source
- Make access_level a keyword argument in GroupMember.add_users_to_group and ProjectMember.add_users_to_projects
- Destroy any requester before adding them as a member
- Improve the way we handle access requesters in Member.add_user
  Instead of removing the requester and creating a new member,
  we now simply accepts their access request. This way, they will
  receive a "access request granted" email.
- Fix error that was previously silently ignored
- Stop raising when access level is invalid in Member, let Rails validation do their work
Signed-off-by: NRémy Coutable <remy@rymai.me>

Signed-off-by: NRémy Coutable <remy@rymai.me>

Signed-off-by: NRémy Coutable <remy@rymai.me>

Signed-off-by: NRémy Coutable <remy@rymai.me>

- For target project show only environments for target branch or with tags
- For source project show only environments for source branch

Groups can enable/disable LFS, but this setting can be overridden at the project level. Admin only

This moves tracking of the pushes since the last Git GC from PostgreSQL
to Redis. This reduces the number of writes on the "projects" table.
This in turn reduces the vacuuming overhead.

The lease used for incrementing the counter has been removed. This lease
was mostly put in place to prevent high database load but this isn't
needed anymore due to the counter now being stored in Redis.

Fixes gitlab-org/gitlab-ce#22125

Use a permissions of user to access all dependent projects from CI jobs (this also includes a container images, and in future LFS files)

This commit makes sure that the project icon is
being read from the default branch instead of
'master'

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5142#note_14073464

Use just SQL to check is a user can admin_issue on a project

Tradeoff

- we duplicate how we check admin_issue in a SQL relation in the Ability class

Also, mutualize AccessRequests and Members endpoints for Group &
Project.
New API documentation for the AccessRequests endpoints.
Signed-off-by: NRémy Coutable <remy@rymai.me>

Instead of redirecting from the project service to the service and back to the model,
put all destruction code in the service. Also removes a possible source of failure
where run_after_commit may not destroy the project.

This is in preparation to address the DB load caused by the counting in
gitlab-com/infrastructure#303.

developer cannot push to protected branch when project is empty or he has not been granted permission to do so

squashed - fixed label and milestone association problems, updated specs and refactored reader class a bit

1. Remove `Project#developers_can_push_to_protected_branch?` since it
   isn't used anymore.

2. Remove `Project#developers_can_merge_to_protected_branch?` since it
   isn't used anymore.

Helping to diagnose #20178