Use keycloak configuration mechanism and add a 'swh auth config' command

Add configuration file argument to auth command group

Use keycloak default configuration and defaults method to load and merge
configuration (env > params > user configuration file > default auth
configuration > defaultvalues)

Add swh auth config command which can generate a token by providing a
username (password will be asked by a prompt), or verify a provided
token. If the token is valid user can save the authentication
configuration with token to authentication configuration file which
default to auth.yml