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>

spec/components/budgets/investments/votes_component_spec.rb

@@ -23,8 +23,21 @@ describe Budgets::Investments::VotesComponent, type: :component do
 
         render_inline component
 
+        expect(page).to have_button count: 1, disabled: :all
         expect(page).to have_button "Support", disabled: true
       end
+
+      it "shows the button to remove support when users have supported the investment" do
+        user = create(:user)
+        user.up_votes(investment)
+        allow(controller).to receive(:current_user).and_return(user)
+
+        render_inline component
+
+        expect(page).to have_button count: 1, disabled: :all
+        expect(page).to have_button "Remove your support"
+        expect(page).to have_button "Remove your support to Renovate sidewalks in Main Street"
+      end
     end
   end
 end