Scene2D: fix crash on destruction


Use a QRhi as the QQuickWindow render target. Make sure the QRhi is
destroyed after QQuickRenderControl.

Pick-to: 6.12 6.11 6.8
Fixes: QTBUG-135853
Change-Id: I59e215188df47c953e4a2007d7b19bb23e818efc
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>
commitff6b19b8236c3c006c0833670efe11207a9bf57f
parentb9d1e25f27c3860591b7f7d358cf0c5f0feec001
authorMauro Persano <mauro.persano@kdab.com>
committerMauro Persano <mauro.persano@kdab.com>
commit timeThu, 27 Aug 2026 13:34:47 +0000