DEV: Move core plugin TL -> group settings (#25355)

* DEV: Change poll_minimum_trust_level_to_create to group based setting

New setting is poll_create_allowed_groups

c.f. https://meta.discourse.org/t/changes-coming-to-settings-for-giving-access-to-features-from-trust-levels-to-groups/283408

* DEV: Move styleguide_admin_only to group based setting

Not exactly a TL -> group change, but still part of the
overall effort here:

https://meta.discourse.org/t/changes-coming-to-settings-for-giving-access-to-features-from-trust-levels-to-groups/283408

New setting is styleguide_allowed_groups

plugins/poll/plugin.rb

@@ -206,6 +206,10 @@ after_initialize do
       end
   end
 
+  add_to_serializer(:current_user, :can_create_poll) do
+    scope.user&.staff? || scope.user&.in_any_groups?(SiteSetting.poll_create_allowed_groups_map)
+  end
+
   add_to_class(PostSerializer, :preloaded_polls) do
     @preloaded_polls ||=
       if @topic_view.present?