Strip the "editionable" prefix when displaying document type names

We're adding support for editionable topical events. This requires us
to create a new content type that we've called "editionable_topical_events".
When displaying the name we should strip the editionable bit so it looks
nicer.

app/helpers/admin/new_document_helper.rb

@@ -20,7 +20,7 @@ def new_document_type_list
       .select { |edition_type| can?(:create, edition_type) }
       .map do |edition_type|
       title_value = edition_type.name.underscore
-      title_label = title_value.humanize
+      title_label = title_value.gsub("editionable_", "").humanize
       {
         value: title_value,
         text: title_label,

app/models/editionable_topical_event.rb

@@ -2,4 +2,8 @@ class EditionableTopicalEvent < Edition
   def display_type_key
     "editionable_topical_event"
   end
+
+  def self.format_name
+    "topical event"
+  end
 end

features/support/document_helper.rb

@@ -18,7 +18,7 @@ def begin_drafting_document(options)
     create(:organisation) if Organisation.count.zero?
     visit admin_root_path
     find("li.app-c-sub-navigation__list-item a", text: "New document").click
-    page.choose(options[:type].humanize)
+    page.choose(options[:type].gsub("editionable_", "").humanize)
     click_button("Next")
 
     if options[:locale]