Improve slash command descriptions, support /due tomorrow

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

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

Check for update_issuable permission in Notes::SlashCommandsService

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

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

Some important things to note:

- commands are removed from noteable.description / note.note
- commands are translated to params so that they are treated as normal
  params in noteable Creation services
- the logic is not in the models but in the Creation services, which is
  the right place for advanced logic that has nothing to do with what
  models should be responsible of!
- UI/JS needs to be updated to handle notes which consist of commands
  only
- the `/merge` command is not handled yet

Other improvements:

- Don't process commands in commit notes and display a flash is note is only commands
- Add autocomplete for slash commands
- Add description and params to slash command DSL methods
- Ensure replying by email with a commands-only note works
- Use :subscription_event instead of calling noteable.subscribe
- Support :todo_event in IssuableBaseService

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

There is a race condition in DestroyGroupService now that projects are deleted asynchronously:

1. User attempts to delete group
2. DestroyGroupService iterates through all projects and schedules a Sidekiq job to delete each Project
3. DestroyGroupService destroys the Group, leaving all its projects without a namespace
4. Projects::DestroyService runs later but the can?(current_user,
   :remove_project) is `false` because the user no longer has permission to
   destroy projects with no namespace.
5. This leaves the project in pending_delete state with no namespace/group.

Projects without a namespace or group also adds another problem: it's not possible to destroy the container
registry tags, since container_registry_path_with_namespace is the wrong value.

The fix is to destroy the group asynchronously and to run execute directly on Projects::DestroyService.

Closes #17893

update CHANGELOG

add auto-completion into pipeline

add auto-completion into pipeline

add auto-completion into pipeline

update changelog

modify tests

remove empty lines

add auto-completion into pipeline

update changelog

modify tests

switch text_field_tag into text_field

add test to new field

switch context into describe

Update CHANGELOG

render only commit title

update CHANGELOG

add auto-completion into pipeline

add auto-completion into pipeline

add auto-completion into pipeline

update changelog

modify tests

remove empty lines

add auto-completion into pipeline

update changelog

modify tests

update changelog

Update CHANGELOG

add indetation

add tests to pipeline ref

change file name for tests

change file name for spec tests

remove empty line

rename test it

rename test name

removing unexpected changes

removing unexpected changes2

update changelog

DRY code + fix rubocop

Add more test cases

Append to changelog

DRY changes list

find_url service for merge_requests

use GET for getting merge request links

remove files

rename to get_url_service

reduce loop

add test case for cross project

refactor tiny thing

update changelog

This change simplifies a Pipeline processing by introducing a special new status: created.
This status is used for all builds that are created for a pipeline.
We are then processing next stages and queueing some of the builds (created -> pending) or skipping them (created -> skipped).
This makes it possible to simplify and solve a few ordering problems with how previously builds were scheduled.
This also allows us to visualise a full pipeline (with created builds).

This also removes an after_touch used for updating a pipeline state parameters.
Right now in various places we explicitly call a reload_status! on pipeline to force it to be updated and saved.

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

Since version ruby-2.2.0, method `File::exists?` is deprecated.

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

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

Also, mutualize AccessRequests and Members endpoints for Group &
Project.
New API documentation for the AccessRequests endpoints.

Signed-off-by: Rémy 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.

Currently trees are sorted in the fashion:
- folders
- files
- submodules
with each section sorted alphabetically

This changes to this system:
- folders and submodules (sorted together)
- files