Add submit button to the top of preferences pages (#13068)

* Move submit button to the top of the edit page

* Duplicate save button on long form

* Fix click submit on profile spec

app/views/settings/preferences/other/show.html.haml

@@ -1,7 +1,10 @@
 - content_for :page_title do
   = t('settings.preferences')
 
-= simple_form_for current_user, url: settings_preferences_other_path, html: { method: :put } do |f|
+- content_for :heading_actions do
+  = button_tag t('generic.save_changes'), class: 'button', form: 'edit_preferences'
+
+= simple_form_for current_user, url: settings_preferences_other_path, html: { method: :put, id: 'edit_preferences' } do |f|
   = render 'shared/error_messages', object: current_user
 
   .fields-group