bsbf-openwrt-resources: improve iface type detection and DNS

bsbf-openwrt-resources: improve iface type detection and DNS

To find the correct network interface to create a network entry for, check
which driver is driving the network interface.

Restrict creating a network entry with DHCP client to network interfaces
driven by the cdc_ether, r8152, rndis_host, or ipheth driver.

Ensure UCI section name derived from interface name is proper.

Do not disable using DNS servers advertised by the ISP. This was a
requirement of bsbf-bonding. We can now do this as we transparently proxy
all DNS traffic to Xray which resolves queries.

Do not exit non-zero as it's useless.

Signed-off-by: Chester A. Unal <redacted>