🛡️ Save app settings.

When saving app settings, set the app for which this update applies. Explicitly set the app to null to apply the update to all apps. Account-scoped settings ignore app entirely and are always saved against the caller; settings that belong to the whole install require the ServerSettings.Update capability.<br /><hr /><h3>🛡️ Requires one of these Capabilities: <code>ServerSettings.Update</code></h3>