tools: add BigInt to globals

PR-URL: https://github.com/nodejs/node/pull/21237


Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Yuta Hiroto <hello@hiroppy.me>
Reviewed-By: Ujjwal Sharma <usharma1998@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>