Scramble input windows during fuzzing

Add functionality of scrambling windows for the dispatcher fuzzer.
This allows greater coverage of the dispatcher code.

Also, skip events with ACTION_SCROLL because they might contain an
invalid number of pointers, and they won't correctly be rejected because
we aren't verifying them right now.

Bug: 287342122
Test: FUZZER=inputflinger_input_dispatcher_fuzzer; m $FUZZER && ASAN_OPTIONS=detect_odr_violation=0 $ANDROID_HOST_OUT/fuzz/x86_64/$FUZZER/$FUZZER
Change-Id: I6715ee0327cb5cde76996f1c6a80ceba15030aef