Root should not have to authenticate as another user to change that user's password

Currently, when changing a user's local password, we require authentication as that user:

```
sudo passwd @.onmicrosoft.com
Enter your local password:
>
```

Root should be able to change the local password of a user without authenticating as that user, same as for Unix accounts:
```
sudo passwd foo
New password:
```

Trace the password-change path used by `sudo passwd @.onmicrosoft.com` and compare it with the Unix `sudo passwd foo` flow. Done means root can change another user's local password without authenticating as that user, while the existing user-password behavior remains appropriate.

Written by the indexing model from the issue text.