module: standardize strip shebang behaviour

When loading a module, Node needs to finds the end
of a shebang comment by searching for a \r or \n character.
This behaviour is now standardized into a dedicated
internal module function

Refs: https://github.com/nodejs/node/issues/12180
PR-URL: https://github.com/nodejs/node/pull/12202


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>