Fix wrong ARIA attribute in dashboard actions form

Using a `data-toggle` attribute, which we do since commit 07fd5084f,
made Foundation generate an `aria-expanded` attribute to a radio button,
but this attribute can't be present in radio buttons. This makes sense,
since the main purpose of a radio button in a form is to choose an
option, not to show/hide content.

This resulted in the following error when checking the page with Axe:

```
Found 1 accessibility violation:

aria-allowed-attr: Elements must only use supported ARIA attributes
(critical)
https://dequeuniversity.com/rules/axe/4.10/aria-allowed-attr?application=axeAPI
The following 2 nodes violate this rule:

  Selector: #dashboard_action_action_type_proposed_action
  HTML: <input data-toggle="request_to_administrators short_description"
               type="radio" value="proposed_action" checked="checked"
               name="dashboard_action[action_type]"
               id="dashboard_action_action_type_proposed_action"
               aria-expanded="true"
               aria-controls="request_to_administrators">
  Fix all of the following:
    - ARIA attribute is not allowed: aria-expanded="true"

  Selector: #dashboard_action_action_type_resource
  HTML: <input data-toggle="request_to_administrators short_description"
               type="radio" value="resource"
               name="dashboard_action[action_type]"
               id="dashboard_action_action_type_resource"
               aria-expanded="true"
               aria-controls="request_to_administrators">
  Fix all of the following:
    - ARIA attribute is not allowed: aria-expanded="true"
```

So we're using custom JavaScript instead. We're also making the
`short_description` field act as intended; since the changes in commit
07fd5084f it was never shown because it had the `hide` HTML class and it
didn't have a `data-toggler` attribute.

app/assets/javascripts/admin/dashboard/actions/form.js

@@ -0,0 +1,21 @@
+(function() {
+  "use strict";
+  App.AdminDashboardActionsForm = {
+    initialize: function() {
+      $("input[name='dashboard_action[action_type]']").on({
+        change: function() {
+          switch ($(this).val()) {
+          case "proposed_action":
+            $("#request_to_administrators").hide();
+            $("#short_description").hide();
+            break;
+          case "resource":
+            $("#request_to_administrators").show();
+            $("#short_description").show();
+          }
+        }
+      }).filter("[checked]").trigger("change");
+    }
+  };
+}).call(this);
+

app/assets/javascripts/application.js

@@ -169,6 +169,7 @@ var initialize_modules = function() {
     App.ColumnsSelector.initialize();
   }
   App.AdminBudgetsWizardCreationStep.initialize();
+  App.AdminDashboardActionsForm.initialize();
   App.AdminMachineLearningScripts.initialize();
   App.AdminPollShiftsForm.initialize();
   App.AdminTenantsForm.initialize();

app/helpers/admin/proposal_dashboard_actions_helper.rb

@@ -8,8 +8,4 @@ module Admin::ProposalDashboardActionsHelper
   def default_actions
     %w[polls email poster]
   end
-
-  def css_for_resource(action)
-    "hide" if action == "proposed_action"
-  end
 end

app/views/admin/dashboard/actions/_form.html.erb

@@ -5,9 +5,7 @@
     <%= f.label :action_type %>
     <% ::Dashboard::Action.action_types.keys.each do |action_type_value| %>
       <span class="margin-right">
-        <%= f.radio_button :action_type,
-                           action_type_value,
-                           data: { toggle: "request_to_administrators short_description" } %>
+        <%= f.radio_button :action_type, action_type_value %>
       </span>
     <% end %>
   </div>
@@ -16,9 +14,7 @@
     <%= f.check_box :active %>
   </div>
 
-  <div id="request_to_administrators"
-       class="small-12 column margin-bottom <%= css_for_resource(@dashboard_action.action_type) %>"
-       data-toggler=".hide">
+  <div id="request_to_administrators" class="small-12 column margin-bottom">
     <%= f.check_box :request_to_administrators %>
   </div>
 
@@ -28,7 +24,7 @@
   <div class="small-12 column">
     <%= f.text_field :title %>
 
-    <div id="short_description" class="hide">
+    <div id="short_description">
       <%= f.text_field :short_description %>
     </div>
 

spec/system/admin/dashboard/actions_spec.rb

@@ -73,7 +73,17 @@ describe "Admin dashboard actions", :admin do
     end
 
     scenario "Updates the action" do
+      expect(page).to have_checked_field "Proposed action"
+      expect(page).to have_unchecked_field "Resource"
+      expect(page).not_to have_field "Short description"
+      expect(page).not_to have_field "Include in the resource a button to " \
+                                     "request the resource from administrators"
+
+      choose "Resource"
+      check "Include in the resource a button to request the resource from administrators"
+
       fill_in "Title", with: "Great action!"
+      fill_in "Short description", with: "And awesome too!"
       click_button "Save"
 
       expect(page).to have_content "Great action!"