Push virtio-net interface renaming into userspace (#2).

The first attempt to do the renaming in userspace did not fully work,
because the framework will enumerate the list of interfaces before they
are up, and then fail if any new interfaces appear up after booting. This
was hitting us because ril-daemon will not rename the eth0 interface to
rmnet0 until very late in the boot sequence, after this enumeration has
already completed.

We can leave the older workaround in place, as it is still very useful
for testing, but this workaround will supersede it once it has been
added to the init script.

Bug: 78482534
Test: "/vendor/bin/rename_netiface wlan0 wlan1" works
Change-Id: I4b6b70b3b1f72fe244f857d8088d8f7647636700