Allow sending event data asynchronously to api.honeycomb.com, add support to configure generating events to STDOUT

[robwdux]

We are using AWS Lambda and AWS Cloudwatch would like the ability same as what is provided in the Golang Beeline.

performance - allow trading user facing latency with http synchronous calls for a slight delay in event data arriving at Honeycomb in addition to Cloudwatch costs

durability - allows buffering data with Cloudwatch/Kinesis if necessary at times (don't drop any event data on the floor)

reliability/determinism - had issues with Lambda / Node non-async handler / callback with event loop due to having to have startTrace outside async functions.

Also noted here

In the Honeycomb Serverless stack, we emit structured events to logfiles, and then use lambda functions that upload these logs to Honeycomb

[toshok]

so there is a way to get event traffic to stdout:

require("honeycomb-beeline")({
  transmission: "writer"
});

but there's a libhoney issue with quoting the output, fixed in https://github.com/honeycombio/libhoney-js/pull/73. we'll need to land that fix + bump the libhoney dep here.

[toshok]

The fix for quoting required adding a new transmission type, so the above snippet will become this, post libhoney release:

require("honeycomb-beeline")({
  transmission: "console"
});

[robwdux]

thanks again @toshok for this. When transmission is set to console, may the writekey not be required? .writeKey must be a non-empty string