We can extend the policy in EE for additional behavior

Previously we used @user, but this changed to local_assigns[:user]
so we could pass a second variable to the view from an EE module

Since we were already using current_user librally there it makes sense
to replace the remaining usages.

See: https://docs.gitlab.com/ee/development/module_with_instance_variables.html

- Improves spacing between account buttons on Profile
- AccountsController#show uses locals instead of instance variables
- New `display_providers_on_profile?` helper method
- Adds `render_if_exists` for GroupSAMl unlink buttons

See: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/8682

Enables frozen string for the following:

* app/controllers/dashboard/**/*.rb
* app/controllers/explore/**/*.rb
* app/controllers/google_api/**/*.rb
* app/controllers/groups/**/*.rb
* app/controllers/import/**/*.rb
* app/controllers/instance_statistics/**/*.rb
* app/controllers/ldap/**/*.rb
* app/controllers/oauth/**/*.rb
* app/controllers/profiles/**/*.rb

Partially addresses #47424.

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

Added in disable button for 2fa

Closes #13854

* improve UI
* add authorization
* add separate page for oauth applications

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>