Don't allow to modify questions for started polls

Adding, modifiying, and/or deleting questions for an already started
poll is far away from being democratic and can lead to unwanted side
effects like missing votes in the results or stats.

So, from now on, only modifiying questions will be possible only if
the poll has not started yet.

app/components/admin/poll/questions/form_component.html.erb

@@ -12,10 +12,10 @@
         <%= f.hidden_field :poll_id, value: question.poll.id %>
       <% else %>
         <div class="small-12 medium-6 large-4 column">
-          <% select_options = Poll.all.map { |p| [p.name, p.id] } %>
           <%= f.select :poll_id,
                         options_for_select(select_options),
-                        prompt: t("admin.questions.index.select_poll") %>
+                        prompt: t("admin.questions.index.select_poll"),
+                        hint: t("admin.questions.form.poll_help") %>
         </div>
       <% end %>
     </div>

app/components/admin/poll/questions/form_component.rb

@@ -2,9 +2,18 @@ class Admin::Poll::Questions::FormComponent < ApplicationComponent
   include TranslatableFormHelper
   include GlobalizeHelper
   attr_reader :question, :url
+  delegate :can?, to: :helpers
 
   def initialize(question, url:)
     @question = question
     @url = url
   end
+
+  private
+
+    def select_options
+      Poll.all.select { |poll| can?(:create, Poll::Question.new(poll: poll)) }.map do |poll|
+        [poll.name, poll.id]
+      end
+    end
 end

app/components/admin/poll/questions/table_actions_component.html.erb

@@ -0,0 +1,3 @@
+<%= render Admin::TableActionsComponent.new(question, actions: actions) do |table_actions| %>
+  <%= table_actions.action(:answers, text: t("admin.polls.show.edit_answers")) %>
+<% end %>

app/components/admin/poll/questions/table_actions_component.rb

@@ -0,0 +1,14 @@
+class Admin::Poll::Questions::TableActionsComponent < ApplicationComponent
+  attr_reader :question
+  delegate :can?, to: :helpers
+
+  def initialize(question)
+    @question = question
+  end
+
+  private
+
+    def actions
+      [:edit, :destroy].select { |action| can?(action, question) }
+    end
+end