Implement NodeJS 14 fs.rm

[jcubic]

fs.rm is a new API in NodeJS fs module, that allows running recursive delete of directories. I can be handy in isomorphic-git/isomorphic-git#1383

[mojavelinux]

This is related to #71. Note that in newer versions of Node, the recursive option is now deprecated on rmdir. The rm function has replaced it. See https://nodejs.org/api/fs.html#fs_fspromises_rmdir_path_options