Add button to Admin Account details page to view the instance if non-local user

app/views/admin/accounts/show.html.haml

@@ -1,6 +1,10 @@
 - content_for :page_title do
   = @account.pretty_acct
 
+- content_for :heading_actions do
+  - unless @account.local?
+    = link_to t('admin.accounts.view_instance'), admin_instance_path(@account.domain), method: :post, class: 'button'
+
 - if @account.instance_actor?
   .flash-message.notice
     %strong= t('accounts.instance_actor_flash')

config/locales/en.yml

@@ -165,6 +165,7 @@ en:
       unsuspended_msg: Successfully unsuspended %{username}'s account
       username: Username
       view_domain: View summary for domain
+      view_instance: View instance
       warn: Warn
       web: Web
       whitelisted: Allowed for federation