vbox: Replace virReportError() with vboxReportError()

vbox: Replace virReportError() with vboxReportError()

Now that we have vboxReportError() which reports VirtualBox
errors too, we can switch the code to use the former. And since
the vboxReportError() is designed to behave exactly like
virReportError() we can do that almost everywhere, regardless of
the source of the error.

There are a few exceptions though, for instance, when
initializing VirtualBox SDK (we don't have all the objects needed
for querying exceptions yet), or when invalid combination of
arguments was passed to an API of ours, or when a function from
other module (e.g. src/conf/) failed.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>