This patch adds a module that emits StatsD statistics about Asterisk
endpoints. This includes:
* A GAUGE statistic for endpoint states, tracking how many endpoints are in
a particular state.
* A GAUGE statistic for each endpoint, counting the number of channels
currently associated with an endpoint.
ASTERISK-25572
Change-Id: If7e1333c5aeda8d136850b30c2101c0ee1c97305