Bug 1719855 - Route preventDefaulted touchmove event information to APZ properly...

Bug 1719855 - Route preventDefaulted touchmove event information to APZ properly. r=botond

This change includes three things;

1) Keep two different touch blocks alive during handling a long-tap event,
   one is for the long-tap, the other one is the original block started with
   touchstart.
2) Wait a content response again once after a long-tap event was processed
3) Unconditionally invoke ContentReceivedInputBlockCallback from APZEventState
   for touchmove events so that it will properly route to APZ even if a content
   response for the touchstart has already delivered to APZ.

With these now content responses for `contextmenu` events are handled by the
long-tap block, content responses for touch events are handled by the original
touch block respectively. As a result, `DoLongPressPreventDefaultTest` in
TestGestureDetector.cpp starts processing touch events in APZ thus we observe
a RequestContentRepaint call there, the test content isn't scrolled though. It
will change in the next commit.

Depends on D176479

Differential Revision: https://phabricator.services.mozilla.com/D176480