v8: integrate node-heapdump into core

Adds `v8.writeHeapSnapshot(filename)` with impl adapted
from the `node-heapdump` module.

Also, adds a v8.getHeapSnapshot() alternative that returns
a Readable Stream

PR-URL: https://github.com/nodejs/node/pull/26501


Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>