src: mark ArrayBuffers with free callbacks as untransferable

More precisely, make them untransferable if they were created through
*our* APIs, because those do not follow the improved free callback
mechanism that V8 uses now. All other ArrayBuffers can be transferred
between threads now, the assumption being that they were created in a
clean way that follows the V8 API on this.

This addresses a TODO comment.

Refs: https://github.com/nodejs/node/pull/30339#issuecomment-552225353

PR-URL: https://github.com/nodejs/node/pull/30475


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: David Carlier <devnexen@gmail.com>