Requests session persistence from the portal.
A persistent session can be restored using the restore token, see [method@InputCaptureSession.set_restore_token].
This method can only be called for a session created with [method@Portal.create_input_capture_session2] and only before [ method@InputCaptureSession.start] has been called. It has no effect otherwise.
The default persistence is none.
| this |
a [class@InputCaptureSession] |
| persistence |
the session persistence for this session |