Query can_be_associated_with_topical_events before rendering form

Currently, the topical event form rendering is only gate-kept around
the temporary 'Flipflop' feature flag whilst config-driven topical
events are under development. And this flag only controls the
'topical event documents' association rendering, rather than the
legacy 'topical event' association.

If/when we come to migrate topical events, we'll need to
consolidate the two controller test helper methods:

- should_allow_association_with_topical_event_documents_when_configurable_document_types_enabled
- should_allow_association_with_topical_events

...which should be made easier by making use of the
can_be_associated_with_topical_events conditional.

Author: ChrisBAshton

app/views/admin/editions/_topical_event_fields.html.erb

@@ -1,35 +1,38 @@
-<% cache_if edition.topical_event_ids.empty?, "#{taggable_topical_events_cache_digest}-design-system" do %>
-  <%= render "govuk_publishing_components/components/select_with_search", {
-    id: "edition_topical_event_ids",
-    name: "edition[topical_event_ids][]",
-    include_blank: true,
-    label: "Topical events",
-    heading_size: "m",
-    options: TopicalEvent.order(:name).map do |topical_event|
-      {
-        text: topical_event.name,
-        value: topical_event.id,
-        selected: edition.topical_event_ids.include?(topical_event.id),
-      }
-    end,
-    multiple: true,
-  } %>
-<% end %>
-<% if Flipflop.enabled?(:configurable_document_types) %>
-  <%= render "govuk_publishing_components/components/select_with_search", {
-    id: "edition_topical_event_document_ids",
-    name: "edition[topical_event_document_ids][]",
-    include_blank: true,
-    label: "Topical events (experimental)",
-    hint: "Topical events created via the documents menu will appear here",
-    heading_size: "m",
-    options: StandardEdition.where(configurable_document_type: "topical_event").order(:title).map do |topical_event|
-      {
-        text: topical_event.title,
-        value: topical_event.document_id,
-        selected: edition.topical_event_document_ids.include?(topical_event.document_id),
-      }
-    end,
-    multiple: true,
-  } %>
+<% if edition.can_be_associated_with_topical_events? %>
+  <h2 class="govuk-heading-m">Topical events</h2>
+  <% cache_if edition.topical_event_ids.empty?, "#{taggable_topical_events_cache_digest}-design-system" do %>
+    <%= render "govuk_publishing_components/components/select_with_search", {
+      id: "edition_topical_event_ids",
+      name: "edition[topical_event_ids][]",
+      include_blank: true,
+      label: "Topical events",
+      heading_size: "m",
+      options: TopicalEvent.order(:name).map do |topical_event|
+        {
+          text: topical_event.name,
+          value: topical_event.id,
+          selected: edition.topical_event_ids.include?(topical_event.id),
+        }
+      end,
+      multiple: true,
+    } %>
+  <% end %>
+  <% if Flipflop.enabled?(:configurable_document_types) %>
+    <%= render "govuk_publishing_components/components/select_with_search", {
+      id: "edition_topical_event_document_ids",
+      name: "edition[topical_event_document_ids][]",
+      include_blank: true,
+      label: "Topical events (experimental)",
+      hint: "Topical events created via the documents menu will appear here",
+      heading_size: "m",
+      options: StandardEdition.where(configurable_document_type: "topical_event").order(:title).map do |topical_event|
+        {
+          text: topical_event.title,
+          value: topical_event.document_id,
+          selected: edition.topical_event_document_ids.include?(topical_event.document_id),
+        }
+      end,
+      multiple: true,
+    } %>
+  <% end %>
 <% end %>