test(qemu): add test_qmp_protocol (78 tests) and test_vm (47 tests)
QMP protocol tests use QEMU QMP spec JSON vectors for version,
greeting, message parsing, command serialization, run_state, errors,
timestamps, and event data.
VM tests cover config builder pattern and to_args argument generation
for network modes, display types, serial variants, disk formats,
chardev, channels, and combined configurations.