This adds an AES-GCM 256bit encryption layer for storage for sensitive items. This is only TOTP secrets for the time being but this may be expanded later. This will require a configuration change as per https://www.authelia.com/docs/configuration/migration.html#4330.
Closes#682
This commit replaces github.com/spf13/viper with github.com/knadh/koanf. Koanf is very similar library to viper, with less dependencies and several quality of life differences. This also allows most config options to be defined by ENV. Lastly it also enables the use of split configuration files which can be configured by setting the --config flag multiple times.
Co-authored-by: Amir Zarrinkafsh <nightah@me.com>
