This adds `DisplacementEvent` to fix delta coordinate transformations
for drag events, to be used instead of `PositionEvent`.
Drag Events now expose the start and end position, as well as the delta,
correctly transformed by the camera and zoom.
This also ensures that drag events, once starts, do not get lost if the
drag update leaves the component bounds.
* if you are using `DragUpdateEvent` events, the `devicePosition`,
`canvasPosition`, `localPosition`, and `delta` are deprecated as they
are unclear.
* use `xStartPosition` to get the position at the start of the drag
event ("from")
* use `xEndPosition` to get the position at the end of the drag event
("to")
* if you want the delta, use `localDelta`. it now already considers the
camera zoom. no need to manually account for that
* now you keep receiving drag events for the same component even if the
mouse leaves the component (breaking)
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Co-authored-by: Lukas Klingsbo <lukas.klingsbo@gmail.com>
