feat(ext/node): expand diagnostics_channel coverage - #34243

## Summary

Implements the `diagnostics_channel` (and `tracingChannel`) emissions
that previously-absent Node compat tests rely on, plus fixes a few
preexisting polyfill bugs.

New channel emissions:

- `console.{log,info,debug,warn,error}` publish args to per-method
channels **before** formatting, so subscribers can mutate the args and
see the mutation reflected in output.
- `child_process` channel fires for each new `ChildProcess` (covers
`cluster.fork`). `tracingChannel('child_process.spawn')` publishes start
/ end / error with Node's "end XOR error" semantics. As part of this
`PermissionDenied` now maps to an asynchronous `EACCES` error event on
the child when uid/gid weren't requested (matching Node's `execve`
failure path); the EPERM-sync-throw path is preserved for uid/gid setup
failures.
- `worker_threads` channel fires per `Worker` construction.
- `tracingChannel('module.require')` wraps `Module.prototype.require`
with `{ parentFilename, id }` context.
- `net.client.socket` moved from the `net.connect()` factory to
`Socket.prototype.connect`, so all three client entry points
(`net.connect`, `net.createConnection`, `new net.Socket().connect`)
publish exactly once. TLS sockets (`tls.connect` via `TLSSocket extends
Socket`) now publish too.
- `tracingChannel('net.server.listen')` publishes `asyncStart` at the
top of `Server.prototype.listen` (with the original options object, so
ad-hoc fields survive), `asyncEnd` on `'listening'`, and `error` on
`'error'`.
- `http2.client.stream.bodyChunkSent` fires from
`ClientHttp2Stream._write` / `_writev` with `{ stream, writev, data,
encoding }`, honoring the writable internals' `allBuffers` flag so
single-buffer writers see a flat Buffer array.
`http2.client.stream.bodySent` fires from `_final`, including when no
chunks were sent.

Polyfill fixes shaken out by the new tests:

- `Channel.subscribe`/`unsubscribe` now snapshot the subscriber array
via `slice` + `pushApply`, and `publish` captures the local array
reference, so unsubscribe-during-publish still delivers to the remaining
subscribers (`test-diagnostics-channel-sync-unsubscribe`).
- `WeakRefMap`'s finalizer skips deletion when a fresh `WeakRef` for the
same key already holds a live value, fixing the GC race where a
re-created channel would be evicted out from under a live caller
(`test-diagnostics-channel-gc-race-condition`).
- `tracingChannel(0)` now reports `["string", "object",
"TracingChannel"]` so the formatted message matches Node's
(`test-diagnostics-channel-tracing-channel-args-types`).

Out of scope (left for follow-ups):

- `tracingChannel('module.import')` for dynamic `import()` — needs a
host-side dynamic-import hook in `deno_core`/`cli`, since
`core.compileFunction` doesn't accept a per-script dynamic-import
callback. Tests: `test-diagnostics-channel-module-import[-error]`.
- `test-console-diagnostics-channels` expects `process.stdout.write` to
be hijackable, which requires routing the global `console` through
Node's `Console` instance in Node-compat mode. The channel publishing is
in place; only the global-console wiring is missing.
- `test-diagnostics-channel-http2-client-stream-{created,start}` exposes
a pre-existing http/2 push ordering issue where push `created`/`start`
can outpace the request stream's publish in certain configurations.

Closes denoland/orchid#149

## Test plan

- `cargo test --test node_compat -- diagnostics-channel` — newly-added
entries pass; existing entries unchanged.
- `tools/format.js`
- `tools/lint.js --js`
- CI: verifies the network-bound tests (this worker VM has seccomp
filters that block listen(), so the http2/net body and listen tests
couldn't be verified locally and are added to config.jsonc to run on
CI).

---------

Co-authored-by: divybot <[email protected]>
Co-authored-by: Divy Srivastava <[email protected]>