[9/n Dispatcher refactor] Move computeTouchOcclusionInfo to WindowInfos

In this CL we
1. Moves computeTouchOcclusionInfo to  WindowInfo subclass.
2. Moves dumpWindowForTouchOcclusion to anonymous namespace.
3. Move subclass definitions before all private functions.

Bug: 367661487
Bug: 245989146
Test: atest inputflinger_tests
Flag: EXEMPT refactor
Change-Id: Iccf5b53d1754990a29891ca2172132c7dbab2642