Use toggle_select action for legislation proposals

The `update` action is usually expected to behave the same way it does
everywhere else, which is updating a record using the `params` hash.

The name `toggle_select` comes from the name we use in a similar
situation for budget investments.

app/controllers/admin/legislation/proposals_controller.rb

@@ -9,15 +9,10 @@ class Admin::Legislation::ProposalsController < Admin::Legislation::BaseControll
     @proposals = @proposals.send("sort_by_#{@current_order}").page(params[:page])
   end
 
-  def update
-    @proposal.selected = !@proposal.selected
-
-    if @proposal.save
-      notice = t('admin.legislation.proposals.update.notice')
-    else
-      notice = t('admin.legislation.proposals.update.error')
+  def toggle_selection
+    @proposal.toggle :selected
+    @proposal.save!
+    redirect_to admin_legislation_process_proposals_path,
+                notice: t('admin.legislation.proposals.update.notice')
   end
-    redirect_to admin_legislation_process_proposals_path, notice: notice
-  end
-
 end

app/views/admin/legislation/proposals/_select_proposal.html.erb

@@ -5,4 +5,8 @@
      button_text = t("admin.legislation.proposals.index.select")
      clas = 'button hollow expanded'
    end %>
-<%= link_to button_text, admin_legislation_process_proposal_path(proposal.process, proposal), method: 'PUT', class: clas %>
+
+<%= link_to button_text,
+            toggle_selection_admin_legislation_process_proposal_path(proposal.process, proposal),
+            method: :patch,
+            class: clas %>

config/routes/admin.rb

@@ -194,7 +194,9 @@ namespace :admin do
   namespace :legislation do
     resources :processes do
       resources :questions
-      resources :proposals
+      resources :proposals do
+        member { patch :toggle_selection }
+      end
       resources :draft_versions
     end
   end