feature request: add `cp` command

[sdarwin]

Add a cp command, based on nodejs cp.

https://nodejs.org/api/fs.html

fsPromises.cp(src, dest[, options])

with the recursive option.

To be compatible with both ZenFS and nodejs.

(Or perhaps lightning-fs is in maintenance mode and so this will not be planned. Still worth asking.)

[jcubic]

You can create a PR to add this.