* This will be used in certprovider tests where we would want more than one server and client certs.
* Also, updated existing usages of these certs to point to the new files.
* Also copy over the required certs/key files. This avoids the example gomodule from depending on gRPC testdata package which should be able to change independently.
* Fix interop test's SAN.
Easwar Swaminathan