[Android] Harden RenderWidgetHostViewAndroid deferred teardown

Following crrev.com/c/7957800, RenderWidgetHostViewBase teardown is
deferred while synchronous input dispatch is active on the stack.
During this window host() is null and the native view is detached.

- Pin OnMouseWheelEvent() with ScopedInputDispatchPin, matching
  OnTouchEvent() and OnMouseEvent().
- Add TouchSelectionControllerClientManagerAndroid::Detach() and call
  it from ShutdownAndDisconnect() before hiding selection UI so
  synchronous selection callbacks no-op.
- Add destroy_pending() guards to SetNeedsAnimate() and remaining
  RWHVA methods that dereference host() during the deferred window.

Bug: 517016413, 535749304
Change-Id: I501c2131cff4c461183dd10d2082da2388360a19
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/8419054
Auto-Submit: Aman Verma <amanvr@google.com>
Reviewed-by: Jonathan Ross <jonross@chromium.org>
Commit-Queue: Jonathan Ross <jonross@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1699183}