Check for redundant windows inside WindowInfos

Recently, our team has seen traces where dispatcher is taking a long
time to run - sometimes, more than 22 milliseconds. That's way longer
than the expected ~ 0.3 milliseconds for the entire inputflinger.

After examining the traces, I noticed that there's a lot of time spent
in both findTouchedWindowTargets and dispatchInputEvent. It appears that
we are trying to dispatch one input event multiple times to the same
channel, dreamOverlay.

One way this could be possible if we receive multiple, redundant windows.

In this CL, we add a crash to identify and get out of this bad state.

Bug: 311142655
Test: TEST=inputflinger_tests; m $TEST && $ANDROID_HOST_OUT/nativetest64/$TEST/$TEST
Change-Id: I2170928d1bb1e591b9c93b42dd86827e86a0c7fb