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

- Update PO file

Ruby 2.6 introduced `Enumerable#filter`, which takes no arguments.
Attempting to call `filter` on an `ActiveRecord::Relation` with a scope
will fail with a `wrong number of arguments (given 1, expected 0)`
message because the `Enumerable#filter` implementation overrides the
delegated `ActiveRecord::Relation#filter` method.

To make Admin::UsersController compatible with Ruby 2.6, rename
`User.filter` to `User.filter_items`.

Previously, if you entered a username in the URL manually to view a
specific user, the lookup was done case-sensitively, despite usernames
being case-insensitive, often resulting in a 404. We now use the same
`find_routable!` logic as the non-admin Users controller.

Adds gitlab.impersonation_enabled config option defaulting to true to
keep the current default behaviour.

Only the act of impersonation is modified, impersonation token
management is not affected.

Enables frozen string for the following:

* app/controllers/*.rb
* app/controllers/admin/**/*.rb
* app/controllers/boards/**/*.rb
* app/controllers/ci/**/*.rb
* app/controllers/concerns/**/*.rb

Partially addresses #47424.

This whitelists all existing offenses for the various CodeReuse cops, of
which most are triggered by the CodeReuse/ActiveRecord cop.

This reverts merge request !14148

Revert "Merge branch '35012-navigation-add-option-to-change-navigation-color-palette' into 'master'"

This reverts merge request !13619

Add a rubocop rule to check if a method 'redirect_to' is used without explicitly set 'status' in 'destroy' actions of controllers