feat(typescript): auto-enable project-wide code intelligence

On the first JS/TS file opened in a config-less project, create a
jsconfig.json so vtsls scopes the whole project (cross-file Find Usages,
Rename, Go to Definition) and show an unobtrusive toast with See Config /
Enable TypeScript / Learn more. The toast uses a new reusable SUBTLE
NotificationUI style and opens instantly (instantOpen).

Deleting the config opts out (remembered per project via a 'created'
flag, so it is not recreated); the Problems panel then shows a re-enable
row for JS/TS files. Always creates jsconfig.json (editor-only, never
affects builds) which still scopes .ts files. Desktop-only; skipped in
test windows.

Author: abose

docs/API-Reference/widgets/NotificationUI.md

@@ -74,6 +74,7 @@ CSS class names for notification styles.
 | SUCCESS | <code>string</code> | <code>&quot;style-success&quot;</code> | 
 | ERROR | <code>string</code> | <code>&quot;style-error&quot;</code> | 
 | DANGER | <code>string</code> | <code>&quot;style-danger&quot;</code> | 
+| SUBTLE | <code>string</code> | <code>&quot;style-subtle&quot;</code> | 
 
 <a name="module_widgets/NotificationUI..CLOSE_REASON"></a>