Add an option to zip incident report

Incident reports are getting bigger as we add more sections. Add an
option (-z, default off) to zip incident report.

Bug: 150160547
Test: atest incidentd_test
Test: adb shell incident -z -p EXPLICIT | gunzip | ./out/soong/host/linux-x86/bin/aprotoc --decode=android.os.IncidentProto --proto_path=./ --proto_path=external/protobuf/src frameworks/base/core/proto/android/os/incident.proto
Change-Id: I7c8ff1d91df842c200462ee29f15feae68e62739