qemu: use controller alias when constructing device/controller args

qemu: use controller alias when constructing device/controller args

This makes sure that that the commandlines generated for devices and
controller devices are all using the alias that has been set in the
controller's object as the id of the controller, rather than
hardcoding a printf (or worse, encoding exceptions to the standard
${controller}${index} into the logic)

Since this "fixes" the controller name used for the sata controller,
the commandline arg for the sata controller in the sata test case had
to be adjusted to be "sata0" instead of "ahci0". All other tests
remain unchanged, verifying that the patch causes no other functional
change.

Because the function that finds a controller alias based on a device
def requires a pointer to the full domainDef in order to get the list
of controllers, the arglist of a few functions had to have this added.