Fix event parsing

ART tests are failing with the introduction of aosp/2320257.

The issue is that PacketDispatcher assumes that is a packet
is not a response to a cmd, it is an Event:Composite which
is incorrect. It could also be a JDWP extension event such
as DDM.

Bug: 262643398
Bug: 286794967
Test: Used the following tests

mkdir master-art; cd master-art
repo init -u  https://android.googlesource.com/platform/manifest  -b master-art --partial-clone --clone-filter=blob:limit=10M
. build/envsetup.sh
lunch armv8-eng
art/tools/buildbot-build.sh --host
art/tools/run-libjdwp-tests.sh --mode=host --test org.apache.harmony.jpda.tests.jdwp.VirtualMachine_ExitTest#testExit001
(cherry picked from https://android-review.googlesource.com/q/commit:4fcd0e358265d763d9e64e518c0f5e3db6d16406)
Merged-In: I9bfd325975b4ab9b4a556adb221ab7a249f7c491
Change-Id: I9bfd325975b4ab9b4a556adb221ab7a249f7c491
Cherrypick a fix to apache-harmony