New JVM runtime environment metrics

[roberttoyonaga]

What are you trying to achieve?

I'd like to add process.runtime.jvm.memory.allocation, process.runtime.jvm.cpu.monitor.wait, process.runtime.jvm.cpu.monitor.blocked, process.runtime.jvm.cpu.count, and process.runtime.jvm.cpu.context_switch metrics to the runtime environment metrics.

Additional context.
Metric gathering implementations for these new metrics already exist in a basic form in https://github.com/open-telemetry/opentelemetry-java-instrumentation/tree/main/instrumentation/runtime-telemetry-jfr/library
Once the details around these new metrics are decided, I can update the implementations.

Please see original discussion in this PR and at the Java + Instrumentation SIG.

JFR streaming would be used to gather these metrics. This feature has only been available since JDK 14 so these metrics would only be supported for JDK17+. I've made a note of this in the draft PR for these proposed changes to the semantic conventions.

Please see the draft PR here open-telemetry/opentelemetry-specification#3352 that has more information on each of the new metrics.