The previous implementation iterated across the entire patch set
to determine the number of lines added, deleted, and changed. Rugged
has a native method `Rugged::Diff#stat` that does this already,
which appears to be a little faster and require less RAM than doing
this ourselves.

Improves performance in #41524

- Add a Gitlab::Git::Conflict::Resolution class to encapsulate
resolution data
- Simplify conflict file collection assembly

Closes gitaly#825

When searching for issues, an additional subquery
is added which filters only issues in a project. If global context is
used (no project is specified) this query filters all projects user has
access to.

In that case we can skip this filter because filtering only projects
user has access to is added anyway.

The filter is used only if a custom project context is specified

Related to #40540

In this case the project will get the minimum between both
visibilities.

If that visibility is restricted, then a lower level will be picked.

Closes #41457

When searching for merge requests, an additional subquery
is added which by default filters only merge requests which belong
to source or target project user has permission for.

This filter is not needed because more restrictive filter
which checks if user has permission for target project
is used in the query.

So unless a custom projects filter is used by user, it's possible
to skip the default projects filter and speed up the final query.

Related to #40540

By importing this Ruby code into gitlab-rails (and gitaly-ruby), we avoid
200ms of startup time for each gitlab_projects subprocess we are eliminating.

By not having a gitlab_projects subprocess between gitlab-rails / sidekiq and
any git subprocesses (e.g. for fork_project, fetch_remote, etc, calls), we can
also manage these git processes more cleanly, and avoid sending SIGKILL to them

I've followed the [upgrade guide](https://github.com/thoughtbot/factory_bot/blob/4-9-0-stable/UPGRADE_FROM_FACTORY_GIRL.md) and ran these two commands:

```
grep -e FactoryGirl **/*.rake **/*.rb -s -l | xargs sed -i "" "s|FactoryGirl|FactoryBot|"
grep -e factory_girl **/*.rake **/*.rb -s -l | xargs sed -i "" "s|factory_girl|factory_bot|"
```
Signed-off-by: NRémy Coutable <remy@rymai.me>

This allows us to avoid relying on telnet / netcat being installed

i.e.
Using compare and swap we update the expires_at value.
The thread that actually is able to update this value will also set
the cache holding method_call enabled state