feat(instrumentation-runtime-node): add active resource gauge

[sfozz]

Which problem is this PR solving?

Add a gauge to monitor the Active Resources that are keeping the event loop alive. This metric is recommended to be monitored to avoid saturation and starvation issues.

• allows detection of resource leaks (sockets and file descriptors for example)

Short description of the changes

• Add gauge metric v8js.active_resource
• Add metric attribute v8sj.active_resource.type

Reference

• https://nodejs.org/api/process.html#processgetactiveresourcesinfo

[trentm]

@pichlermarc @maryliag Thoughts on whether the requirement here should be that we update semconv first? IIUC, the original definition of v8 semconv metrics was perhaps whatever this instrumentation already just happened to be emitting? Do you recall, Marylia?

[maryliag]

Thoughts on whether the requirement here should be that we update semconv first?

I think the best approach is indeed updating the semconv first. @sfozz can you make the changes here first?

IIUC, the original definition of v8 semconv metrics was perhaps whatever this instrumentation already just happened to be emitting? Do you recall, Marylia?

First we did the conventions, then the instrumentation was added, was a little back and forward, but the implementation was based on the sem conv, and at that time we chose the most requested metrics.

Also, @sfozz please add tests to this PR