Split window limit minimize Change into its own transition

Before this CL we would add minimize changes to existing app launch
transitions through DTC#handleRequest(). With this CL we instead use
runOnIdle() (called from onTransitionReady()) to check whether to
launch a new minimize transition.
The benefit of using runOnIdle() instead of handleRequest() is that in
runOnIdle() we have information about all the collected Changes in the
transition so we can make a more informed decision on whether to
minimize. This new approach supports edge-cases such as launching task
trampolines and opening a new tab in Chrome.

Bug: 404549853
Bug: 356337427
Flag: com.android.window.flags.enable_desktop_task_limit_separate_transition
Test: DesktopTasksLimiterTest, DesktopMixedTransitionHandlerTest
Change-Id: I9758ce691bb1f838b00f262b46ceede0802efd8a