Allow users to remove their support on investments

Note we don't cast negative votes when users remove their support. That
way we provide compatibility for institutions who have implemented real
negative votes (in case there are / will be any), and we also keep the
database meaningful: it's not that users downvoted something; they
simply removed their upvote.

Co-Authored-By: Javi Martín <javim@elretirao.net>
Co-Authored-By: Julian Nicolas Herrero <microweb10@gmail.com>

app/controllers/management/budgets/investments/votes_controller.rb

@@ -1,6 +1,7 @@
 class Management::Budgets::Investments::VotesController < Management::BaseController
   load_resource :budget, find_by: :slug_or_id
   load_resource :investment, through: :budget, class: "Budget::Investment"
+  load_and_authorize_resource through: :investment, through_association: :votes_for, only: :destroy
 
   def create
     @investment.register_selection(managed_user)
@@ -11,7 +12,15 @@ class Management::Budgets::Investments::VotesController < Management::BaseContro
           notice: t("flash.actions.create.support")
       end
 
-      format.js
+      format.js { render :show }
+    end
+  end
+
+  def destroy
+    @investment.unliked_by(managed_user)
+
+    respond_to do |format|
+      format.js { render :show }
     end
   end
 end