fuzz: use FQName to identify our fuzz target

Main motiviation is that using FQName makes it easier to interact with
libvintf, which will be needed for static fuzzer executables.

Test: m vts_proto_fuzzer; using
"--vts_target_fq_name=android.hardware.light@2.0::ILight" works as
expected
Change-Id: I13a1e6a06baed3c3c5811b2e0a6ce81a6e1259d5
4 files changed