Doc: Override DragHandler.accepted* and marginHEADdev

DragHandler docs have been showing TapHandler code snippets, because
both DragHandler and TapHandler inherit properties from
PointerDeviceHandler, which is abstract and uses TapHandler code
snippets in some of its property documentation.

Override documentation for acceptedDevices, acceptedModifiers,
acceptedPointerTypes and margin by adding to the DragHandler class, and
add testable snippets for a couple of them. draggableGridView is adapted
from examples/quick/draganddrop/views/gridview.qml.

Fixes: QTBUG-119866
Pick-to: 6.8 6.7 6.5 6.2
Change-Id: I9f98d831ec1691c84da6a38a7625f9aba086cebf
Reviewed-by: Santhosh Kumar <santhosh.kumar.selvaraj@qt.io>

0 files changed, 0 insertions, 0 deletions