util: implement util.getSystemErrorName()

Reimplement uv.errname() as internal/util.getSystemErrorName() to
avoid the memory leaks caused by unknown error codes
and avoid calling into C++ for the error names. Also
expose it as a public API for external use.

PR-URL: https://github.com/nodejs/node/pull/18186
Refs: http://docs.libuv.org/en/v1.x/errors.html#c.uv_err_name


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>