net: dns: add query support for additional types CNAME, SRV, and TXT

These types are useful for IoT deployments and should be available
thru the resolver interface to get the data. The SRV is especially
useful to find services on the local network when not using a dns-sd
deployment and just something like Avanhi or Bonjour.

Signed-off-by: Charles Hardin <ckhardin@gmail.com>