Added support for AAAA record for coredns and included unit test.
Fixed function names in comments for Google and AWS tests to match
actual test name in this area.
There can be multiple DNS resource records for a given name. They can
vary by type, ttl, rrdata and a number of various other parameters. It
is incorrect to return a single resource record for a given name.
This change updates the Get interface to return multiple records for a given
name and uses this list in the federated service controller to perform
DNS operations.
Having an A-record and a CNAME-record in the tests led to a confusion
that dns providers support such configurations. This change avoids
that confusion by putting only compatible records for the same domain
name in the tests.