Fix updating of QQuick3DTexture

Update when and only when content of QQuick3DTexture changes.
Similar changes were already done for QQuick3DItem2D.
Fixes lancelot qml stream tests.

Task-number: QTBUG-83213
Change-Id: I9ef62b1b8ace404c7b038ae23303469ecf56afb5
Reviewed-by: Tomi Korpipää <tomi.korpipaa@qt.io>
Reviewed-by: Andy Nichols <andy.nichols@qt.io>