src: move C++ binding/addon related code into node_binding{.h, .cc}

This patch:

- Moves the C++ binding/addon related code out of
  node_internals.h/node.cc and into dedicated files
  node_binding.h/node_binding.cc, and only puts the code resued
  by other files into the header.
- Introduce a node::binding namespace so that code exposed to
  other files can be easily recognized.

PR-URL: https://github.com/nodejs/node/pull/24701


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>