Add federation relay support (#7998)

* Add federation relay support

* Add admin UI for managing relays

* Include actor on relay-related activities

* Fix i18n

app/views/admin/relays/_relay.html.haml

@@ -0,0 +1,21 @@
+%tr
+  %td
+    %samp= relay.inbox_url
+  %td
+    - if relay.enabled?
+      %span.positive-hint
+        = fa_icon('check')
+        = ' '
+        = t 'admin.relays.enabled'
+    - else
+      %span.negative-hint
+        = fa_icon('times')
+        = ' '
+        = t 'admin.relays.disabled'
+  %td
+    - if relay.enabled?
+      = table_link_to 'power-off', t('admin.relays.disable'), disable_admin_relay_path(relay), method: :post, data: { confirm: t('admin.accounts.are_you_sure') }
+    - else
+      = table_link_to 'power-off', t('admin.relays.enable'), enable_admin_relay_path(relay), method: :post, data: { confirm: t('admin.accounts.are_you_sure') }
+
+    = table_link_to 'times', t('admin.relays.delete'), admin_relay_path(relay), method: :delete, data: { confirm: t('admin.accounts.are_you_sure') }

app/views/admin/relays/index.html.haml

@@ -0,0 +1,20 @@
+- content_for :page_title do
+  = t('admin.relays.title')
+
+.simple_form
+  %p.hint= t('admin.relays.description_html')
+  = link_to @relays.empty? ? t('admin.relays.setup') : t('admin.relays.add_new'), new_admin_relay_path, class: 'block-button'
+
+- unless @relays.empty?
+  %hr.spacer
+
+  .table-wrapper
+    %table.table
+      %thead
+        %tr
+          %th= t('admin.relays.inbox_url')
+          %th= t('admin.relays.status')
+          %th
+      %tbody
+        = render @relays
+

app/views/admin/relays/new.html.haml

@@ -0,0 +1,13 @@
+- content_for :page_title do
+  = t('admin.relays.add_new')
+
+= simple_form_for @relay, url: admin_relays_path do |f|
+  = render 'shared/error_messages', object: @relay
+
+  .field-group
+    = f.input :inbox_url, as: :string, wrapper: :with_block_label
+
+  .actions
+    = f.button :button, t('admin.relays.save_and_enable'), type: :submit
+
+  %p.hint.subtle-hint= t('admin.relays.enable_hint')