Enable StatsD UDP listening using IPv4 or IPv6 explicitly

[mindscratch]

Feature Request

Opening a feature request kicks off a discussion.

Proposal:

Enable the StatsD input plugin to listen on UDP using IPv4 or IPv6 explicitly.

Current behavior:

The StatsD input plugin listens for UDP traffic using whichever versions of the Internet Protocol are supported by the system its running on. For example, on macOS Sierra it'll use IPv4 and IPv6. On a CentOS 7 server with IPv6 enabled it'll use IPV6 only.

Desired behavior:

For the StatsD input plugin to enable the use of IPv4, IPv6 or either (based on whats supported by the host).

Use case: [Why is this important (helps with prioritizing requests)]

There are known issues with being able to send UDP packets to processes in docker containers, in particular UDP with IPv4 is expected to work.