Merge commit '55e7c08a83547424024bac311d5459cb82cf6dae' into glitch-soc/merge-upstream

Conflicts:
- `app/models/user_settings.rb`:
  Upstream added a constraint on a setting textually close
  to glitch-soc-only settings.
  Applied upstream's change.
- `lib/sanitize_ext/sanitize_config.rb`:
  Upstream added support for the `translate` attribute on a few elements,
  where glitch-soc had a different set of allowed elements and attributes.
  Extended glitch-soc's allowed attributes with `translate` as upstream did.
- `spec/validators/status_length_validator_spec.rb`:
  Upstream refactored to use RSpec's `instance_double` instead of `double`,
  but glitch-soc had changes to tests due to configurable max toot chars.
  Applied upstream's changes while keeping tests against configurable max
  toot chars.

app/models/user_settings.rb

@@ -15,7 +15,7 @@ class UserSettings
   setting :show_application, default: true
   setting :default_language, default: nil
   setting :default_sensitive, default: false
-  setting :default_privacy, default: nil
+  setting :default_privacy, default: nil, in: %w(public unlisted private)
   setting :default_content_type, default: 'text/plain'
   setting :hide_followers_count, default: false
 
@@ -79,7 +79,10 @@ class UserSettings
 
     raise KeyError, "Undefined setting: #{key}" unless self.class.definition_for?(key)
 
-    typecast_value = self.class.definition_for(key).type_cast(value)
+    setting_definition = self.class.definition_for(key)
+    typecast_value = setting_definition.type_cast(value)
+
+    raise ArgumentError, "Invalid value for setting #{key}: #{typecast_value}" if setting_definition.in.present? && setting_definition.in.exclude?(typecast_value)
 
     if typecast_value.nil?
       @original_hash.delete(key)