Add a fake resolvconf executable to verify that the right nameserver
addresses were actually committed by iwd. Again use unique nameserver
addresses to reduce the possibility that the test succeeds by pure luck.
Extend test_ip_address_match to support IPv6 and to test the
netmask/prefix length while it reads the local address since those are
retrieved using the same API.
Modify testNetconfig to validate the prefix lengths, change the prefix
lengths to be less common values (not 24 bits for IPv4 or 64 for IPv6),
minor cleanup.
If running multiple tests testNetconfig would fail due to the
hardcoded wln0 in the dhcpd.conf file. dhcpd can actually start
by passing in the interface to the run command rather than
inside the config file.
Tests that DHCP using IWD's internal netconfig functions properly.
The actual IP address assignment is not verified, but since IWD does
not signal the connection as successful unless DHCP succeeds we
can assume it was successful by checking that the device is connected.
The process of actually starting dhcpd and configuring the interfaces
is quite simple so it was left in the autotest itself. If (or when)
more tests require IP capabilities (p2p, FILS, etc) this could be
moved into test-runner itself and be made common. The reason I did not
put it in there now is a) because this is the only test and b) more
complex DHCP cases are likely to develop and may require more than this
simplistic setup (like multiple APs/interfaces)
