feat(metrics): Collect process and Go runtime metrics

[hairyhenderson]

Description

A downside of using a custom Prometheus registry rather than the global one is that it has no collectors available. Generally it's quite useful to have the Go collector as well as the Process collector enabled, to track memory, goroutine, file descriptor, CPU, and other metrics useful for observing any Go process.

This PR enables those two.

Before:

$ curl -s http://localhost:1034/metrics | wc -l
29
$ curl -s http://localhost:1034/metrics | grep go_
$

After:

$ curl -s http://localhost:1034/metrics | wc -l
122
$ curl -s http://localhost:1034/metrics | grep go_goroutines
# HELP go_goroutines Number of goroutines that currently exist.
# TYPE go_goroutines gauge
go_goroutines 13
$

Closes issue(s)

None - small enough change I didn't think it necessary!

Checklist

• I have tested this code
• I have added unit test to cover this code
• I have updated the documentation (README.md and /website/docs)
• I have followed the contributing guide

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.74%. Comparing base (42aa171) to head (4f773a1).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2708   +/-   ##
=======================================
  Coverage   84.73%   84.74%           
=======================================
  Files         111      111           
  Lines        5162     5164    +2     
=======================================
+ Hits         4374     4376    +2     
  Misses        624      624           
  Partials      164      164           

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[thomaspoignant]

Hey thanks for this one, I agree this is simple enough not to have any issue.
🚀