fix(node): Fixes and improvements to ANR detection

[timfish]

This PR:

• Adds support for pm2 (closes Application Not Responding (ANR) feature breaks use with PM2 #9131)
  • Passes SENTRY_ANR_CHILD_PROCESS environment variable to the child process for reliable child process detection
  • To support cluster mode, process.env.pm_exec_path is used for entryScript over process.argv[1]
    • It's worth noting that in cluster mode, an ANR child process is started for every forked cluster process. If you cluster on 8 cores, this will result in 8 ANR process with roughly 400MB of memory overhead.
• Changes to use spawn rather than fork since fork in Electron does not run a fully Electron capable node process so we can't get all the required context
• Disables tracing and session tracking for ANR child process
• Handles inspector port already in use
  • inspector.open() defaults to port 9229. When inspector.url() returns undefined we now try the next port
• Improves logging to aid in future debugging of issues