Allow users to select and save the preferred duo device and method, depending on availability in the duo account. A default enrollment URL is provided and adjusted if returned by the duo API. This allows auto-enrollment if enabled by the administrator.
Closes#594. Closes#1039.
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>
