net,src: refactor writeQueueSize tracking

Currently, writeQueueSize is never used in C++ and barely used
within JS. Instead of constantly updating the value on the JS
object, create a getter that will retrieve the most up-to-date
value from C++.

For the vast majority of cases though, create a new prop on
Socket.prototype[kLastWriteQueueSize] using a Symbol. Use this
to track the current write size, entirely in JS land.

PR-URL: https://github.com/nodejs/node/pull/17650


Reviewed-By: Anna Henningsen <anna@addaleax.net>