Add optional file encryption for user credentials configuration

[svartkanin]

This is a follow-up PR for #3276 to fix #1111.

It'll add a option to store the data in the user_configuration.json file in encrypted form. While saving the configuration files there's a new optional step to encrypt the content and if chosen provide an encryption key. The newly introduced cryptography module will handle the encryption by generating a salt and using Argon2id to encrypt the JSON data with the provided password.

The stored encryption data will look like

$argon2id$<salt>$<encrypted_data>

When providing an encrypted user_credentials.json file, there are 3 ways to provided the encryption key:

• Via a new argument parameter --creds-decryption-key
• By setting an environment variable ARCHINSTALL_CREDS_DECRYPTION_KEY
• If none of the above is specified a prompt on startup will be presented to manually enter the encryption key

[codefiles]

What is the reason for using the Password class and not just a str throughout? When it is being used in these changes, it is initialized with plaintext and then is only ever used as plaintext. This looks like unnecessary complexity.

[svartkanin]

@Torxed any concerns with this or can we merge it?

[Torxed]

Looks good to me!