Event loop metrics

[dacevedo12]

Is your feature request related to a problem?

Cooperative multitasking works great until something doesn't cooperate. It is then critical to identify situations where the event loop becomes blocked for too long

Describe the solution you'd like

A histogram showing the event loop lag would be helpful

Describe alternatives you've considered

Implementing it myself

Additional context

• https://github.com/newrelic/newrelic-python-agent/blob/main/newrelic/core/loop_node.py
• Runtime instrumentation opentelemetry-js-contrib#1106
• https://github.com/siimon/prom-client/blob/0f444cd38e4c7074991270106c270f731bafddb8/lib/metrics/eventLoopLag.js