Add password hash authentication method

[spacefrogg]

This is an update of the previous attempt to bring purely user-controlled hash-based authentication to hyprlock.

It is based on #585 and brings a hyprlock-pwhash helper binary to create the right hash config in the right location. The location of the hash config file can be chosen via the auth:sodium:secret_file config option and the --config option to hyprlock-pwhash.

The auth:sodium:secret_file config option can be:

1. a stem which gets completed to "main config file location" + OPT + ".conf"
2. a relative path (with at least ./... one slash) which gets extended to "main config file location" + OPT
3. an absolute path that is taken as is.

To be conservative, the PAM and sodium authentication methods are mutually exclusive. That may be unnecessary.

Closes #573

[PointerDilemma]

I am currently working on pulling the authentication stuff out of hyprlock to also use it for the pollkitagent. It would be cool to add this there.

What did you change on top of #573?

[PointerDilemma]

Also It would be nice to give some reasons why you want to use this over pam authentication.