Add search form to proposals admin index

app/controllers/admin/proposals_controller.rb

@@ -1,12 +1,18 @@
 class Admin::ProposalsController < Admin::BaseController
+  include HasOrders
+  include CommentableActions
   include FeatureFlags
   feature_flag :proposals
 
-  def index
-    @proposals = Proposal.sort_by_created_at.page(params[:page])
-  end
+  has_orders %w[created_at]
 
   def show
     @proposal = Proposal.find(params[:id])
   end
+
+  private
+
+    def resource_model
+      Proposal
+    end
 end