[CON-120] enter new password twice

I think `./useradmin --add-user user1 --new-password pass1` doesn't not need to re-enter password since it could be used in scripts.
I don't think there's any significant difference. The reason behind this is that, `--grant` and `--revoke` are the existing implementation which are already there. Obviously, that implementation uses bytes and I didn't modified anything.

We could change them all to String instead of bytes? What you think?

We