TrustedPresentationListener: Fix occlusion calculation for invisible windows

TrustedPresentationListener (TPL) incorrectly computed occlusion without considering window visibility. This led to potential issues, especially with windows like the IME window, which can remain invisible but still present in the window list.

Future changes will prevent invisible windows from being passed to TPL and input, mitigating similar problems.

Fixes: 404598904
Test: presubmit
Flag: EXEMPT bug fix
Change-Id: I3f61397c5facc54634fec16706b1216d1dbdc69c