Refactor DragDetector and fix a few resizing bugs

There are a few things this CL does:

1. It refactors DragDetector to filter out moves in the slop instead of
   returning a boolean value to let the caller to decide what to do with
   it.
2. It fixes the bug that window decors respond to window moves in the
   slop.
3. It skips the unnecessary transaction at the end of drag resizing
   gesture in TaskPositioner if nothing has changed.
4. It fixes the bug that TaskPositioner uses if the new task bounds is
   empty to decide if there is no change in the task bounds.

Bug: 266448890
Test: Drag resize windows with mice and fingers.
Test: atest WMShellUnitTests

Change-Id: I8e9e1204e841bfd8f730d4091e37955f1f376018