Extract component to show moderation actions

Note that in proposal notifications we're writing the call to
render the component in the same line as the <div class="reply">
definition in order to be able to use the `:empty` selector when the
component renders nothing. No browser matches whitespace with the
`:empty` selector, so we can't add newline characters inside the tag. A
more elegant solution would be extracting the proposal notification
actions to a component and only rendering it if the moderation actions
component is rendered.

spec/system/comments/budget_investments_valuation_spec.rb

@@ -275,7 +275,7 @@ describe "Internal valuation comments on Budget::Investments" do
 
       expect(page).to have_no_css(".comment-votes")
       expect(page).to have_no_css(".js-flag-actions")
-      expect(page).to have_no_css(".js-moderation-actions")
+      expect(page).to have_no_css(".moderation-actions")
     end
   end