Display group/project access requesters separately in admin
## What does this MR do?
It displays the access requesters in a separate list in group & project members pages.
It also harmonize the members counter UI to use `%span.badge` everywhere (in the admin & non-admin members views).
## Are there points in the code the reviewer needs to double check?
No.
## Why was this MR needed?
To not confuse access requesters with actual members.
## What are the relevant issue numbers?
Closes#18871.
## Screenshots
### Group members
| Before | After |
| --------- | ---- |
|  |  |
### Project members
| Before | After |
| --------- | ---- |
|  |  |
### Admin group members
| Before | After |
| --------- | ---- |
|  |  |
### Admin project members
| Before | After |
| --------- | ---- |
|  |  |
## Does this MR meet the acceptance criteria?
- [x] No CHANGELOG since this is related to the original "request access" MR.
- [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)
See merge request !4798
Signed-off-by: Rémy Coutable <remy@rymai.me>
Resolve "Destroying a project causes post_decline_request to be executed"
## What does this MR do?
Ensure we don't send "access request declined" to access requesters when a project is deleted.
## Are there points in the code the reviewer needs to double check?
I've created a service to decouple the notification sending from the AR model.
## Why was this MR needed?
Because there was an issue.
## What are the relevant issue numbers?
Fixes#18755, #18750.
## Does this MR meet the acceptance criteria?
- [x] No CHANGELOG needed.
- [x] Tests
- [x] Added for this feature/bug
- [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)
See merge request !4744
Signed-off-by: Rémy Coutable <remy@rymai.me>
GitLab CI Yaml template dropdown
## What does this MR do?
Make it possible to select a dropdown for an easy start with GitLab CI.
## What are the relevant issue numbers?
Closes#17521
## TODO
- [ ] Backend
- [x] CHANGELOG item
- [x] Fix rubocop failure
- [x] API Support
- [x] New tests
- [x] Add disclaimer to the top of the gitlab-ci.yml
- [ ] Frontend
- [x] New tests
See merge request !4411
Refs dropdown is now loaded async
## What does this MR do?
The refs dropdown is loaded async so not to block the page.
## What are the relevant issue numbers?
Part of #18202
## Screenshots (if relevant)

See merge request !4508
Ensure that group owner cannot request access to a project of their group
## What does this MR do?
It fixes two things:
- 91ad995d69e1a0f8991fd896f1d9febc109273fe Ensure that group owner cannot request access to a project of their group
- ec3ff061148d556757e7cd486cdc6083d77acf34 Ensure group/project owners can see their members' access_level (see the commit message for details)
## Are there points in the code the reviewer needs to double check?
Not really, these are pretty simple fixes.
## Why was this MR needed?
Because there was an issue created!
## What are the relevant issue numbers?
Fixes#18717.
## Does this MR meet the acceptance criteria?
- [x] CHANGELOG is not needed since the bug is only present in a 8.9 RC
- [x] Tests
- [x] Added for this feature/bug
- [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)
See merge request !4729
Don't show 'Leave Project' to group members
## What does this MR do?
It hides the 'Leave Project' button to group members that are not explicitly a member of the project.
## Are there points in the code the reviewer needs to double check?
No.
## Why was this MR needed?
Because there was an issue opened!
## What are the relevant issue numbers?
Fixes#18724.
## Does this MR meet the acceptance criteria?
- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] Tests
- [x] Added for this feature/bug
- [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)
See merge request !4739
+ Move 'Edit Project/Group' out of membership-related partial
+ Show the access request buttons only to logged-in users
+ Put the request access buttons out of in a more visible button
+ Improve the copy in the #remove_member_message helper
Signed-off-by: Rémy Coutable <remy@rymai.me>