src: harden JSStream callbacks

Since these are executing JS code, and in particular parts of that
code may be provided by userland, handle such exceptions in C++.

Refs: https://github.com/nodejs/node/pull/17938#issuecomment-354683850
PR-URL: https://github.com/nodejs/node/pull/18028


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>