Wayland: Send multiple touch events during on multi finger drag-and-drop

When the user starts a window dragging session with touch, an
ET_TOUCH_PRESSED event is dispatched right before the drag is started.
Then, when the drag is finished or canceled, an ET_TOUCH_RELEASE event
is dispatched by WaylandWindowDragController synthetically.

However, currently WaylandWindowDragController always dispatches only
one touch release event regardless of the number of fingers that the
drag is triggered with. This can cause a problem that makes the browser
unresponsive, specifically in Lacros (crbug.com/328726759).

This CL changes WaylandWindowDragController so that it sends as many
touch release (and also touch motion) events as the active touch points.

Bug: b:328726759
Change-Id: I3db9208797787eb2b4172cc5fdfe3a737542d81c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5383708
Commit-Queue: Jun Ishiguro <junis@google.com>
Reviewed-by: Nick Yamane <nickdiego@igalia.com>
Cr-Commit-Position: refs/heads/main@{#1280653}