util: add node.telemetry trace event category

[jasnell]

At the Collaborator Summit, during the session discussing deprecations,
the concept of adding a mechanism to optionally collect targeted
telemetry data was discussed. This PR introduces one possible way
of doing so while giving users complete opt-in control.

This adds a new node.telemetry trace event category and a new
internal telemetry() function that we can selectively place at
key locations within the code. When the node.telemetry trace
category is enabled, the telemetry() function will emit a
trace event, the key use of which shall just be to determine
how many times a particular code path is used.

For instance,

const { telemetry } = require('util/internal/telemetry');

function someCoreFunction(arg) {
  telemetry('SOME_TRACE_ID', `Path used with arg: ${arg}`);
}

By running node.js with the --trace-event-categories=node.telemetry
flag, the trace event log will include the telemetry entries that
can then be optionally shared with the Node.js project.

The trace event is intentionally very simple.

/cc @addaleax @BridgeAR @Fishrock123

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/23480/

[addaleax]

I have a feeling that gathering individual trace events is going to be too heavy for practical telemetry usage, at least for an initial version of it.

[jasnell]

Entirely possible. I don't want to get overly inventive with this however, and I don't want to cache any data, just output and forget.

[jasnell]

Closing this for now. Can revisit later.