Stack is visible if behind docked which is behind pinned stack (1/2)

Handles the case if pip is shown with splitscreen when the stack order
is pinned, docked, current stack, etc (top to bottom). Added a condition
to check to make sure that this order of stacks allows the current stack
to be visible. Also added a condition to not hide docked stack when pip
appears (this only occurs with command line or cts tests); added TODO
for refactor.

Change-Id: I53bd55014c08c60f360b95ed7100ef49778f891b
Fixes: 37294521
Test: run-test CtsServicesHostTestCases
android.server.cts.ActivityManagerPinnedStackTests#
testPinnedStackWithDockedStack