DEV: enable frozen string literal on all files

This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.

Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging

app/controllers/admin/emojis_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_dependency 'upload_creator'
 
 class Admin::EmojisController < Admin::AdminController

app/controllers/admin/flagged_topics_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_dependency 'flag_query'
 
 class Admin::FlaggedTopicsController < Admin::AdminController

app/controllers/admin/flags_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'flag_query'
 
 class Admin::FlagsController < Admin::AdminController

app/controllers/admin/groups_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Admin::GroupsController < Admin::AdminController
   def bulk
   end

app/controllers/admin/impersonate_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Admin::ImpersonateController < Admin::AdminController
 
   def create

app/controllers/admin/permalinks_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Admin::PermalinksController < Admin::AdminController
 
   before_action :fetch_permalink, only: [:destroy]

app/controllers/admin/plugins_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Admin::PluginsController < Admin::AdminController
 
   def index

app/controllers/admin/reports_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_dependency 'report'
 
 class Admin::ReportsController < Admin::AdminController

app/controllers/admin/screened_emails_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Admin::ScreenedEmailsController < Admin::AdminController
 
   def index

app/controllers/admin/screened_ip_addresses_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_dependency 'ip_addr'
 
 class Admin::ScreenedIpAddressesController < Admin::AdminController

app/controllers/admin/screened_urls_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Admin::ScreenedUrlsController < Admin::AdminController
 
   def index

app/controllers/admin/search_logs_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Admin::SearchLogsController < Admin::AdminController
 
   def index

app/controllers/admin/site_settings_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Admin::SiteSettingsController < Admin::AdminController
   rescue_from Discourse::InvalidParameters do |e|
     render_json_error e.message, status: 422

app/controllers/admin/site_texts_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_dependency 'seed_data/categories'
 require_dependency 'seed_data/topics'
 

app/controllers/admin/staff_action_logs_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Admin::StaffActionLogsController < Admin::AdminController
 
   def index
@@ -22,7 +24,7 @@ class Admin::StaffActionLogsController < Admin::AdminController
 
     diff_fields = {}
 
-    output = "<h2>#{CGI.escapeHTML(cur["name"].to_s)}</h2><p></p>"
+    output = +"<h2>#{CGI.escapeHTML(cur["name"].to_s)}</h2><p></p>"
 
     diff_fields["name"] = {
       prev: prev["name"].to_s,

app/controllers/admin/themes_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_dependency 'upload_creator'
 require_dependency 'theme_store/tgz_exporter'
 require 'base64'

app/controllers/admin/user_fields_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Admin::UserFieldsController < Admin::AdminController
 
   def self.columns

app/controllers/admin/users_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_dependency 'user_destroyer'
 require_dependency 'admin_user_index_query'
 require_dependency 'admin_confirmation'

app/controllers/admin/versions_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_dependency 'discourse_updates'
 
 class Admin::VersionsController < Admin::AdminController

app/controllers/admin/watched_words_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Admin::WatchedWordsController < Admin::AdminController
 
   def index

app/controllers/admin/web_hooks_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Admin::WebHooksController < Admin::AdminController
   before_action :fetch_web_hook, only: %i(show update destroy list_events bulk_events ping)