* Limits raw requests to 300 per minute and per raw path.
* Add a new attribute to ApplicationSettings so user can change this
value on their instance.
* Uses Gitlab::ActionRateLimiter to limit the raw requests.
* Add a new method into ActionRateLimiter to log the event into auth.log

Related to https://gitlab.com/gitlab-org/gitlab-ce/issues/48717

CE Port: Log impersonation actions in audit log

See merge request gitlab-org/gitlab-ce!31039

It seems that we missed the backward compatibility support
for profiles in the existing folder.

This commit also fixes some specs to be idempotent
and work in a temporary directory which not always
seems to be the case.

This commit also brings the profile_spec.rb which seems
to be missing.

This change adds audit logs for user impersonation
when an admin starts/stops impersonating
another user.

For both groups_controller and admin/groups_controller

Extend the support for "X-Profile-Token: <token>" to have an additional
header that defines type of profile we are looking for, like:
  X-Profile-Mode: execution
  X-Profile-Mode: memory

* remove feature flag for admin settings
* remove feature flag for domain settings

The /admin panel will now always return an uncached
application setting to ensure it always has the most
current info.

Updating multiple application settings panels through
a single action causes the incorrect action to be shown
when there are errors.  Instead, make each panel action
handle both updating and display.