Add support for locks in google assistant component (#18233)

* Add support for locks in google assistant component

This is supported by the smarthome API, but there is no documentation
for it. This work is based on an article I found with screenshots of
documentation that was erroneously uploaded:

https://www.androidpolice.com/2018/01/17/google-assistant-home-can-now-natively-control-smart-locks-august-vivint-first-supported/

Google Assistant now supports unlocking certain locks - Nest and August
come to mind - via this API, and this commit allows Home Assistant to
do so as well.

Notably, I've added a config option `allow_unlock` that controls
whether we actually honor requests to unlock a lock via the google
assistant. It defaults to false.

Additionally, we add the functionNotSupported error, which makes a
little more sense when we're unable to execute the desired state
transition.

https://developers.google.com/actions/reference/smarthome/errors-exceptions#exception_list

* Fix linter warnings

* Ensure that certain groups are never exposed to cloud entities

For example, the group.all_locks entity - we should probably never
expose this to third party cloud integrations. It's risky.

This is not configurable, but can be extended by adding to the
cloud.const.NEVER_EXPOSED_ENTITIES array.

It's implemented in a modestly hacky fashion, because we determine
whether or not a entity should be excluded/included in several ways.

Notably, we define this array in the top level const.py, to avoid
circular import problems between the cloud/alexa components.

homeassistant/components/google_assistant/smart_home.py

@@ -7,7 +7,9 @@ from homeassistant.util.decorator import Registry
 
 from homeassistant.core import callback
 from homeassistant.const import (
-    CONF_NAME, STATE_UNAVAILABLE, ATTR_SUPPORTED_FEATURES)
+    CLOUD_NEVER_EXPOSED_ENTITIES, CONF_NAME, STATE_UNAVAILABLE,
+    ATTR_SUPPORTED_FEATURES
+)
 from homeassistant.components import (
     climate,
     cover,
@@ -15,6 +17,7 @@ from homeassistant.components import (
     group,
     input_boolean,
     light,
+    lock,
     media_player,
     scene,
     script,
@@ -22,12 +25,13 @@ from homeassistant.components import (
     vacuum,
 )
 
+
 from . import trait
 from .const import (
-    TYPE_LIGHT, TYPE_SCENE, TYPE_SWITCH, TYPE_VACUUM,
+    TYPE_LIGHT, TYPE_LOCK, TYPE_SCENE, TYPE_SWITCH, TYPE_VACUUM,
     TYPE_THERMOSTAT, TYPE_FAN,
     CONF_ALIASES, CONF_ROOM_HINT,
-    ERR_NOT_SUPPORTED, ERR_PROTOCOL_ERROR, ERR_DEVICE_OFFLINE,
+    ERR_FUNCTION_NOT_SUPPORTED, ERR_PROTOCOL_ERROR, ERR_DEVICE_OFFLINE,
     ERR_UNKNOWN_ERROR
 )
 from .helpers import SmartHomeError
@@ -42,6 +46,7 @@ DOMAIN_TO_GOOGLE_TYPES = {
     group.DOMAIN: TYPE_SWITCH,
     input_boolean.DOMAIN: TYPE_SWITCH,
     light.DOMAIN: TYPE_LIGHT,
+    lock.DOMAIN: TYPE_LOCK,
     media_player.DOMAIN: TYPE_SWITCH,
     scene.DOMAIN: TYPE_SCENE,
     script.DOMAIN: TYPE_SCENE,
@@ -80,7 +85,7 @@ class _GoogleEntity:
         domain = state.domain
         features = state.attributes.get(ATTR_SUPPORTED_FEATURES, 0)
 
-        return [Trait(self.hass, state) for Trait in trait.TRAITS
+        return [Trait(self.hass, state, self.config) for Trait in trait.TRAITS
                 if Trait.supported(domain, features)]
 
     @callback
@@ -168,7 +173,7 @@ class _GoogleEntity:
 
         if not executed:
             raise SmartHomeError(
-                ERR_NOT_SUPPORTED,
+                ERR_FUNCTION_NOT_SUPPORTED,
                 'Unable to execute {} for {}'.format(command,
                                                      self.state.entity_id))
 
@@ -232,6 +237,9 @@ async def async_devices_sync(hass, config, payload):
     """
     devices = []
     for state in hass.states.async_all():
+        if state.entity_id in CLOUD_NEVER_EXPOSED_ENTITIES:
+            continue
+
         if not config.should_expose(state):
             continue