policies: remove current request from context.

This refactors Pundit policies to only rely on the current user, not on
the current user and the current HTTP request. In retrospect, it was a
bad idea to include the current request in the Pundit context. It bleeds
out everywhere and there are many contexts (in tests and models) where
we only have the current user, not the current request. The previous
commit got rid of the only two places where we used it.

app/components/comment_component.rb

@@ -7,7 +7,7 @@ class CommentComponent < ApplicationComponent
   def self.with_collection(comments, current_user:, **options)
     dtext_data = DText.preprocess(comments.map(&:body))
     # XXX
-    #comments = comments.includes(:moderation_reports) if Pundit.policy!([current_user, nil], ModerationReport).show?
+    #comments = comments.includes(:moderation_reports) if Pundit.policy!(current_user, ModerationReport).show?
 
     super(comments, current_user: current_user, dtext_data: dtext_data, **options)
   end