Add administrative webhooks (#18510)

* Add administrative webhooks

* Fix error when webhook is deleted before delivery worker runs

config/locales/activerecord.en.yml

@@ -21,6 +21,14 @@ en:
             username:
               invalid: must contain only letters, numbers and underscores
               reserved: is reserved
+        admin/webhook:
+          attributes:
+            url:
+              invalid: is not a valid URL
+        doorkeeper/application:
+          attributes:
+            website:
+              invalid: is not a valid URL
         status:
           attributes:
             reblog:

config/locales/en.yml

@@ -852,6 +852,26 @@ en:
       edit_preset: Edit warning preset
       empty: You haven't defined any warning presets yet.
       title: Manage warning presets
+    webhooks:
+      add_new: Add endpoint
+      delete: Delete
+      description_html: A <strong>webhook</strong> enables Mastodon to push <strong>real-time notifications</strong> about chosen events to your own application, so your application can <strong>automatically trigger reactions</strong>.
+      disable: Disable
+      disabled: Disabled
+      edit: Edit endpoint
+      empty: You don't have any webhook endpoints configured yet.
+      enable: Enable
+      enabled: Active
+      enabled_events:
+        one: 1 enabled event
+        other: "%{count} enabled events"
+      events: Events
+      new: New webhook
+      rotate_secret: Rotate secret
+      secret: Signing secret
+      status: Status
+      title: Webhooks
+      webhook: Webhook
   admin_mailer:
     new_appeal:
       actions:
@@ -916,7 +936,6 @@ en:
   applications:
     created: Application successfully created
     destroyed: Application successfully deleted
-    invalid_url: The provided URL is invalid
     regenerate_token: Regenerate access token
     token_regenerated: Access token successfully regenerated
     warning: Be very careful with this data. Never share it with anyone!

config/locales/simple_form.en.yml

@@ -91,6 +91,9 @@ en:
         name: You can only change the casing of the letters, for example, to make it more readable
       user:
         chosen_languages: When checked, only posts in selected languages will be displayed in public timelines
+      webhook:
+        events: Select events to send
+        url: Where events will be sent to
     labels:
       account:
         fields:
@@ -219,6 +222,9 @@ en:
         name: Hashtag
         trendable: Allow this hashtag to appear under trends
         usable: Allow posts to use this hashtag
+      webhook:
+        events: Enabled events
+        url: Endpoint URL
     'no': 'No'
     recommended: Recommended
     required: