Simplify using helper methods in components

The `use_helpers` method was added in ViewComponent 3.8.0, and it's
included by default in all components since version 3.11.0.

Note we sometimes delegated the `can?` method to the controller instead
of the helpers, for no particularly reason. We're unifying that code as
well.

app/components/layout/locale_switcher_component.rb

@@ -1,5 +1,5 @@
 class Layout::LocaleSwitcherComponent < ApplicationComponent
-  delegate :name_for_locale, :link_list, :current_path_with_query_params, :rtl?, to: :helpers
+  use_helpers :name_for_locale, :link_list, :current_path_with_query_params, :rtl?
 
   def render?
     locales.size > 1