Add multi-factor authentication modules (#15489)

* Get user after login flow finished

* Add multi factor authentication support

* Typings

homeassistant/config.py

@@ -14,14 +14,16 @@ import voluptuous as vol
 from voluptuous.humanize import humanize_error
 
 from homeassistant import auth
-from homeassistant.auth import providers as auth_providers
+from homeassistant.auth import providers as auth_providers,\
+    mfa_modules as auth_mfa_modules
 from homeassistant.const import (
     ATTR_FRIENDLY_NAME, ATTR_HIDDEN, ATTR_ASSUMED_STATE,
     CONF_LATITUDE, CONF_LONGITUDE, CONF_NAME, CONF_PACKAGES, CONF_UNIT_SYSTEM,
     CONF_TIME_ZONE, CONF_ELEVATION, CONF_UNIT_SYSTEM_METRIC,
     CONF_UNIT_SYSTEM_IMPERIAL, CONF_TEMPERATURE_UNIT, TEMP_CELSIUS,
     __version__, CONF_CUSTOMIZE, CONF_CUSTOMIZE_DOMAIN, CONF_CUSTOMIZE_GLOB,
-    CONF_WHITELIST_EXTERNAL_DIRS, CONF_AUTH_PROVIDERS, CONF_TYPE)
+    CONF_WHITELIST_EXTERNAL_DIRS, CONF_AUTH_PROVIDERS, CONF_AUTH_MFA_MODULES,
+    CONF_TYPE)
 from homeassistant.core import callback, DOMAIN as CONF_CORE, HomeAssistant
 from homeassistant.exceptions import HomeAssistantError
 from homeassistant.loader import get_component, get_platform
@@ -166,7 +168,10 @@ CORE_CONFIG_SCHEMA = CUSTOMIZE_CONFIG_SCHEMA.extend({
                     CONF_TYPE: vol.NotIn(['insecure_example'],
                                          'The insecure_example auth provider'
                                          ' is for testing only.')
-                })])
+                })]),
+    vol.Optional(CONF_AUTH_MFA_MODULES):
+        vol.All(cv.ensure_list,
+                [auth_mfa_modules.MULTI_FACTOR_AUTH_MODULE_SCHEMA]),
 })
 
 
@@ -412,7 +417,9 @@ async def async_process_ha_core_config(
     # Only load auth during startup.
     if not hasattr(hass, 'auth'):
         setattr(hass, 'auth', await auth.auth_manager_from_config(
-            hass, config.get(CONF_AUTH_PROVIDERS, [])))
+            hass,
+            config.get(CONF_AUTH_PROVIDERS, []),
+            config.get(CONF_AUTH_MFA_MODULES, [])))
 
     hac = hass.config