Dac: support host name when setting dac node endpoint

This shouldn't fail:

./octez-dac-client send payload to coordinator https://dac-coordinator-test1.gcp.marigold.dev:443 with content ${PAYLOAD}
Error:
  Erroneous command line argument 5 (https://dac-coordinator-test1.gcp.marigold.dev:443).
  Address not in format <rpc_address>:<rpc_port>