Support for no protocol in security group rules

Summary

Our role does not allow us to define security group rules without providing a specific protocol type.

Steps to reproduce

openstack_project_security_groups:
  - name: "egress-traffic"
    rules:
      - direction: "egress"
        remote_ip_prefix: "0.0.0.0/0"

Expected behavior

Rule should be added for every protocol.

Actual behavior

Error.

Possible fixes

Add default(omit) for protocol type.