Update button to skip the govuk-account

The single page notification button component, by default, enforces
creating/signing in to a gov.uk account. It has a default form action
of "/email/subscriptions/single-page/new".
Passing in the optional paramater `skip_account` sets a form action of
"/email-signup" which does not enforce the gov.uk account

See govuk_publishing_components/presenters/single_page_notification_button_helper.rb#L63-L69

app/views/content_items/document_collection.html.erb

@@ -22,7 +22,7 @@
 </div>
 
 <%= render 'shared/publisher_metadata_with_logo' %>
-<%= render 'shared/single_page_notification_button', content_item: @content_item %>
+<%= render 'shared/single_page_notification_button', content_item: @content_item, skip_account: "true" %>
 
 <div class="govuk-grid-row">
   <div class="govuk-grid-column-two-thirds">

app/views/shared/_published_dates_with_notification_button.html.erb

@@ -1,4 +1,5 @@
 <% add_view_stylesheet("published-dates-button-group") %>
+<% skip_account = skip_account || "false" %>
 
 <%= render 'components/published_dates', {
     published: @content_item.published,
@@ -13,6 +14,7 @@
     js_enhancement: @has_govuk_account,
     button_location: "bottom",
     margin_bottom: 3,
+    skip_account: skip_account,
   } if @content_item.has_single_page_notifications? %>
   <%= render "govuk_publishing_components/components/print_link", {
     margin_top: 0,

app/views/shared/_single_page_notification_button.html.erb

@@ -1,6 +1,9 @@
+<% skip_account = skip_account || "false" %>
+
 <%= render 'govuk_publishing_components/components/single_page_notification_button', {
   base_path: @content_item.base_path,
   js_enhancement: @has_govuk_account,
   margin_bottom: 6,
   button_location: "top",
+  skip_account: skip_account,
 } if @content_item.has_single_page_notifications? %>