debugger: add edit-free runtime expression probes to node inspect

[joyeecheung]

Add a non-interactive probe mode to node inspect for inspecting runtime values in a run-to-completion application. This allows users to perform printf-style debugging without having to modify the application code and clean up afterwards, it also supports structured output to be consumed by tools.

This is proposed to be experimental first, so that we can iterate on the interface. There are a few features that would be nice to have but better left for follow-ups to avoid bloating the diff:

• Source map support - which will allow developers to get a trace of ad-hoc interesting values without having to rebuild their apps
• Attaching to a running process with inspector listening on a port - so it can be used to print a trace of ad-hoc interesting values from a local dev server without having to restart it

In this patch, probe mode launches the application, sets one or more source breakpoints, evaluates one expression at each hit, and prints a single text or JSON report containing all the evaluated values when execution ends.

Interface:

node inspect [--json] [--preview] [--timeout=<ms>] [--port=<port>]
  --probe <file>:<line>[:<col>] --expr <expr> ...
  [--] <script> [args...]

For example, to inspect a string in an application without modifying the source:

// cli.js
let maxRSS = 0;
for (let i = 0; i < 2; i++) {
  const { rss } = process.memoryUsage();
  maxRSS = Math.max(maxRSS, rss);
}

$ node inspect --probe cli.js:5 --expr 'rss' cli.js
Hit 1 at cli.js:5
  rss = 54935552
Hit 2 at cli.js:5
  rss = 55083008
Completed

(Prettified JSON to fit in commit message restrictions).

$ node inspect --json --probe cli.js:5 --expr 'rss' cli.js
{"v":1,"probes":[{"expr":"rss","target":["cli.js",5]}],
"results":[
  {"probe":0,"event":"hit","hit":1,
   "result":{"type":"number","value":55443456,
             "description":"55443456"}},
  {"probe":0,"event":"hit","hit":2,
   "result":{"type":"number","value":55574528,
             "description":"55574528"}},
  {"event":"completed"}]}

[joyeecheung]

cc @nodejs/inspector @nodejs/diagnostics

[codecov]

Codecov Report

❌ Patch coverage is 78.50467% with 184 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.73%. Comparing base (dfe438d) to head (4278d22).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/internal/debugger/inspect.js	78.06%	179 Missing and 5 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #62713      +/-   ##
==========================================
- Coverage   89.81%   89.73%   -0.08%     
==========================================
  Files         699      699              
  Lines      216379   217210     +831     
  Branches    41366    41557     +191     
==========================================
+ Hits       194340   194922     +582     
- Misses      14139    14368     +229     
- Partials     7900     7920      +20     

Files with missing lines	Coverage Δ
lib/internal/debugger/inspect_client.js	87.94% <100.00%> (+0.37%)	⬆️
lib/internal/errors.js	97.63% <100.00%> (+<0.01%)	⬆️
lib/internal/debugger/inspect.js	82.51% <78.06%> (-11.43%)	⬇️

... and 29 files with indirect coverage changes

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