Enable more frozen string in app/controllers/

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.

app/controllers/dashboard/application_controller.rb

+# frozen_string_literal: true
+
 class Dashboard::ApplicationController < ApplicationController
   include ControllerWithCrossProjectAccessCheck

app/controllers/dashboard/groups_controller.rb

+# frozen_string_literal: true
+
 class Dashboard::GroupsController < Dashboard::ApplicationController
   include GroupTree

app/controllers/dashboard/labels_controller.rb

+# frozen_string_literal: true
+
 class Dashboard::LabelsController < Dashboard::ApplicationController
   def index
     respond_to do |format|

app/controllers/dashboard/milestones_controller.rb

+# frozen_string_literal: true
+
 class Dashboard::MilestonesController < Dashboard::ApplicationController
   include MilestoneActions

app/controllers/dashboard/projects_controller.rb

+# frozen_string_literal: true
+
 class Dashboard::ProjectsController < Dashboard::ApplicationController
   include ParamsBackwardCompatibility
   include RendersMemberAccess

app/controllers/dashboard/snippets_controller.rb

+# frozen_string_literal: true
+
 class Dashboard::SnippetsController < Dashboard::ApplicationController
   skip_cross_project_access_check :index

app/controllers/dashboard/todos_controller.rb

+# frozen_string_literal: true
+
 class Dashboard::TodosController < Dashboard::ApplicationController
   include ActionView::Helpers::NumberHelper

app/controllers/explore/application_controller.rb

+# frozen_string_literal: true
+
 class Explore::ApplicationController < ApplicationController
   skip_before_action :authenticate_user!

app/controllers/explore/groups_controller.rb

+# frozen_string_literal: true
+
 class Explore::GroupsController < Explore::ApplicationController
   include GroupTree

app/controllers/explore/projects_controller.rb

+# frozen_string_literal: true
+
 class Explore::ProjectsController < Explore::ApplicationController
   include ParamsBackwardCompatibility
   include RendersMemberAccess

app/controllers/explore/snippets_controller.rb

+# frozen_string_literal: true
+
 class Explore::SnippetsController < Explore::ApplicationController
   def index
     @snippets = SnippetsFinder.new(current_user).execute

app/controllers/google_api/authorizations_controller.rb

+# frozen_string_literal: true
+
 module GoogleApi
   class AuthorizationsController < ApplicationController
     def callback

app/controllers/groups/application_controller.rb

+# frozen_string_literal: true
+
 class Groups::ApplicationController < ApplicationController
   include RoutableActions
   include ControllerWithCrossProjectAccessCheck

app/controllers/groups/avatars_controller.rb

+# frozen_string_literal: true
+
 class Groups::AvatarsController < Groups::ApplicationController
   before_action :authorize_admin_group!

app/controllers/groups/boards_controller.rb

+# frozen_string_literal: true
+
 class Groups::BoardsController < Groups::ApplicationController
   include BoardsResponses

app/controllers/groups/children_controller.rb

+# frozen_string_literal: true
+
 module Groups
   class ChildrenController < Groups::ApplicationController
     before_action :group

app/controllers/groups/group_members_controller.rb

+# frozen_string_literal: true
+
 class Groups::GroupMembersController < Groups::ApplicationController
   include MembershipActions
   include MembersPresentation

app/controllers/groups/labels_controller.rb

+# frozen_string_literal: true
+
 class Groups::LabelsController < Groups::ApplicationController
   include ToggleSubscriptionAction

app/controllers/groups/milestones_controller.rb

+# frozen_string_literal: true
+
 class Groups::MilestonesController < Groups::ApplicationController
   include MilestoneActions

app/controllers/groups/runners_controller.rb

+# frozen_string_literal: true
+
 class Groups::RunnersController < Groups::ApplicationController
   # Proper policies should be implemented per
   # https://gitlab.com/gitlab-org/gitlab-ce/issues/45894