The existing QEMU and vbox URI path validation consider
that a privileged user can use both a "/system" and a
"/session" URI. This differs from all the other drivers
that forbids the root user to use "/session" URI.

Let's update virConnectValidateURIPath() to handle these
cases as exceptions, using the already existent 'entityName'
value to handle "QEMU" and "vbox" differently. This allows
us to use the validateURI function in these cases without
changing the existing behavior of other drivers.
Reviewed-by: NCole Robinson <crobinso@redhat.com>
Suggested-by: NCole Robinson <crobinso@redhat.com>
Signed-off-by: NDaniel Henrique Barboza <danielhb413@gmail.com>