Allow setting of default language through config

Setting of locale in controller extracted to Localized concern,
the doorkeeper authorized applications controller moved under
custom namespace with inclusion of Localized, which resolves the
"it sometimes appears in a different random language" bug

app/controllers/oauth/authorizations_controller.rb

@@ -1,9 +1,10 @@
 # frozen_string_literal: true
 
 class Oauth::AuthorizationsController < Doorkeeper::AuthorizationsController
+  include Localized
+
   skip_before_action :authenticate_resource_owner!
 
-  before_action :set_locale
   before_action :store_current_location
   before_action :authenticate_resource_owner!
 
@@ -12,10 +13,4 @@ class Oauth::AuthorizationsController < Doorkeeper::AuthorizationsController
   def store_current_location
     store_location_for(:user, request.url)
   end
-
-  def set_locale
-    I18n.locale = current_user.try(:locale) || I18n.default_locale
-  rescue I18n::InvalidLocale
-    I18n.locale = I18n.default_locale
-  end
 end

app/controllers/oauth/authorized_applications_controller.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+class Oauth::AuthorizedApplicationsController < Doorkeeper::AuthorizedApplicationsController
+  include Localized
+
+  skip_before_action :authenticate_resource_owner!
+
+  before_action :store_current_location
+  before_action :authenticate_resource_owner!
+
+  private
+
+  def store_current_location
+    store_location_for(:user, request.url)
+  end
+end