Store password for REST API feature as Argon2 hash instead of clear text.

[mplieske]

It would be great to enhance the security of the REST API feature by hashing the password in the application.properties as an Argon2 hash.

I know this is not a high security context. Still I would feel better if secrets are encoded. Because why do you even have authentication if the credentials are not stored safely.

[mplieske]

I created PR #199 for this issue.

[mplieske]

I spotted one issue here.

The configuration screen reads the password from the application.properties and loads it into the view. If you already have a configuration for the REST API feature and you want to change something, eg the port, the already hashed password will be hashed and saved.

I will provide a fix for this in the coming days.

Probably we should only save a password if provided a new one and we should not load the password from the application.properties into the view.

In case of no password being present in the application.properties we could display a warning.