Add qemu-* command test cases

The qemu-* commands are explicitly unsupported in RHEL products, so
the testing strategy is mainly focus on return status and libvirtd status after
command been executed.

This depends on PR:
https://github.com/autotest/virt-test/pull/1666
The list could include:
``` 
    "guest-ping"
     "guest-info"
     "guest-sync"
     "guest-sync-delimited"
     "guest-network-get-interfaces"
     "guest-shutdown"--->powertdown/reboot/halt
     "guest-file-open"
     "guest-file-write"
     "guest-file-close"
     "guest-file-read"
     "guest-file-flush"
     "guest-file-seek"
     "guest-suspend-hybrid"
     "guest-suspend-ram"
     "guest-suspend-disk"
     "guest-fsfreeze-status" 
     "guest-fsfreeze-freeze"
     "guest-fsfreeze-thaw"
     "guest-fstrim" 
```
it's not in my plan to cover them all.