Show "not allowed" message on click

Defining a behavior on hover means making it different for people using
a keyboard or a touchscreen (most of the population, nowadays).

In this case, we had an accessibility issue where the message wouldn't
disappear once it appeared. That meant that, after tabbing through all
the links and buttons in, for instance, the debates index, the page
would be filled with "participation not allowed" messages, and in order
to see the information about how many people have voted, reloading the
page was required.

For touchscreen users the behavior was similar to what we get on hover,
although we've found some inconsistencies when trying to support several
elements on the same page.

We think in proposals it makes sense to hide the "support" button when
users click on it, and the same applies to the buttonsto support and
vote investment projects. However, we aren't hiding the buttons to
agree/disagree with a debate in order to keep the information about the
current number of people agreeing and disagreeing visible.

Note we're removing some support spec methods because after these
changes the duplication isn't as obvious as it was in the past.

spec/components/debates/votes_component_spec.rb

@@ -5,11 +5,11 @@ describe Debates::VotesComponent do
   let(:component) { Debates::VotesComponent.new(debate) }
 
   describe "Agree and disagree buttons" do
-    it "is disabled to anonymous users" do
+    it "is shown to anonymous users alongside a reminder to sign in" do
       render_inline component
 
-      expect(page).to have_button "I agree", disabled: true
-      expect(page).to have_button "I disagree", disabled: true
+      expect(page).to have_button "I agree"
+      expect(page).to have_button "I disagree"
       expect(page).to have_content "You must sign in or sign up to continue."
     end