To update existing user, group and set passwd in the filesystem

This example demonstrates how to:

1. We assume the filesystem has a user and group from above example:
   1. A user with username "nvidia2", user-id "1001" and password "driveos".
   2. A group "automotive" with group-id "2001".
2. Update user to username "nvidia3" and keep identifier "1001" and set password to "nvidia3".
3. Update group to groupname "auto" and keep group identifier "2001".
4. The memberships (which are based on UID/GID) are automatically updated in the filesystem.

{
    "Users": {
        "one": {
            "UID": "1001",
            "Username" : "nvidia3",
            "Password": "nvidia3"
        }
    },
    "Groups": {
        "one": {
            "Groupname": "auto",
            "GID": "2001"
        }
    }
}