More advanced data dispatching approach

[astorm]

Update 13.10.2021:
Persistant/Streaming Connection to APM Server
frequency / throughput based, less blocking

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We should investigate how hard it would be to leave a persistent connection to APM Server open. Right now the prototype extension does a single POST per function invocation. This may not be possible due to the freeze/unfreeze cycle of a lambda function and some uncertainty on how persistent connections behave when unfreezing.

One approach to this might be to implement a heuristic in the extension that can detect when the extension is receiving steady traffic and switch into a streaming mode.

Tentatively marking this is a "nice to have", but not necessary for an MVP.

[estolfo]

It seems we can use net.Dial to get a connection, then call Write on the request, passing the connection. If we don't set the Content-Length, the write function will set the transfer encoding to "chunked".