Closes #33423

This ensures the open issues/MR count caches are refreshed properly when
creating new issues or MRs. This MR also includes a change to the cache
keys to ensure all caches are rebuilt on the fly.

This particular problem was not caught in the test suite due to a null
cache being used, resulting in all calls that would use a cache using
the underlying data directly. In production the code would fail because
a newly saved record returns an empty hash in #changes meaning checks
such as `state_changed? || confidential_changed?` would return false for
new rows, thus never updating the counters.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/38061

We were incorrectly stubbing `Issues::MoveService#execute`. This only
caused a failure when another spec caused it to be autoloaded --
`spec/controllers/projects/issues_controller_spec.rb` in this case.

 Update to add all issues to be updated.
 Added functionality, proper tests, documentation and changelog.

Every project page displays a navigation menu that in turn displays the
number of open issues and merge requests. This means that for every
project page we run two COUNT(*) queries, each taking up roughly 30
milliseconds on GitLab.com. By caching these numbers and refreshing them
whenever necessary we can reduce loading times of all these pages by up
to roughly 60 milliseconds.

The number of open issues does not include confidential issues. This is
a trade-off to keep the code simple and to ensure refreshing the data
only needs 2 COUNT(*) queries instead of 3. A downside is that if a
project only has 5 confidential issues the counter will be set to 0.

Because we now have 3 similar counting service classes the code
previously used in Projects::ForksCountService has mostly been moved to
Projects::CountService, which in turn is reused by the various service
classes.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/36622

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

`:mailer` is needed to pick it easily, while
`type: :mailer` is needed for picking it automatically for
tests located in spec/mailers/*_spec.rb

It's a bit complicated in spec/services/notification_service_spec.rb
but we'll leave it alone for now.

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

Remove superfluous lib: true, type: redis, service: true, models: true, services: true, no_db: true, api: true

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

Marking an issue as a duplicate will now also add an upvote on behalf of the author on the original issue.

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/27070

Deprecate "chat commands" in favor of "slash commands"

We looked for things like:

 - `slash commmand`
 - `slash_command`
 - `slash-command`
 - `SlashCommand`

Use the EnforcedStyleForMultiline: no_comma option.

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

- Ignore JS fixtures
- Ignore qa directory
- Rewrite concern specs to put concern name first