Objectives:
- Facilitate the generation of valid password hashes that can be used with
the `server user --user-password` CLI command.
- Encapsulate implementation details of password hashing in
the `user` package.
Adds a new `server user hash-password` CLI command to generate the
hash from a supplied password.
Modifies the `server user set/add --user-password-hash` CLI command
to accept the password hash generated using the `hash-password`
command.
Adds `GetNewProfile(ctx, rep, username)` helper to move implementation
details to the `user` package.
Includes CLI and unit tests.
Cleans up and removes unused functions.