<!--- Verify first that your feature was not already discussed on GitHub -->
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##### SUMMARY
elb_network_lb and elb_target_group should support UDP, currently only HTTP, HTTPS and TCP are supported by ansible.

Based on the current pages, UDP and TCP_UDP are supported as protocols:
- https://docs.aws.amazon.com/elasticloadbalancing/latest/network/create-listener.html
- https://docs.aws.amazon.com/elasticloadbalancing/latest/network/create-target-group.html

##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
- elb_target_group
- elb_network_lb

##### ADDITIONAL INFORMATION
It would be useful to use UDP as a protocol for an NLB, additionally, attached target groups would need to support UDP.

TCP_UDP is another protocol that it would be useful to add support for (a port that would take TCP or UDP traffic and not care)

<!--- Paste example playbooks or commands between quotes below -->
```yaml
    - name: Create logstash target group
      elb_target_group:
        name: logstash_bunyan_production_tg
        protocol: udp
        port: 5600
        vpc_id: "{{ vpc_facts.vpcs[0].id }}"
        state: present

    - name: Create nlb
      elb_network_lb:
        name: logstash_nlb
        subnets: "{{ private_subnets + public_subnets }}"
        health_check_path: "/"
        health_check_port: "9600"
        health_check_protocol: "http"
        protocol: "udp"
        port: "5600"
        listeners:
          - Protocol: UDP
            Port: 5600
            DefaultActions:
              - Type: forward
                TargetGroupName: logstash_bunyan_production_tg
        state: present
```

<!--- HINT: You can also paste gist.github.com links for larger files -->

from __future__ import (absolute_import, division, print_function)
__metaclass__ = type
ANSIBLE_METADATA = {'metadata_version': '1.1',
                    'status': ['preview'],
                    'supported_by': 'community'}
DOCUMENTATION = '''
---
module: elb_network_lb
short_description: Manage a Network Load Balancer
description:
    - Manage an AWS Network Elastic Load Balancer. See
      U(https://aws.amazon.com/blogs/aws/new-network-load-balancer-effortless-scaling-to-millions-of-requests-per-second/) for details.
version_added: "2.6"
requirements: [ boto3 ]
author: "Rob White (@wimnat)"
options:
  cross_zone_load_balancing:
    description:
      - Indicates whether cross-zone load balancing is enabled.
    default: false
    type: bool
  deletion_protection:
    description:
      - Indicates whether deletion protection for the ELB is enabled.
    default: false
    type: bool
  listeners:
    description:
      - A list of dicts containing listeners to attach to the ELB. See examples for detail of the dict required. Note that listener keys