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 change implements yamllint and adjusts all yaml files to abide by our linting setup. This excludes config.template.yml as this will be done in an alternate commit.