Support templating MQTT triggers (#45614)

* Add support for limited templates (no HASS access)

* Pass variables to automation triggers

* Support templates in MQTT triggers

* Spelling

* Handle trigger referenced by variables

* Raise on unsupported function in limited templates

* Validate MQTT trigger schema in MQTT device trigger

* Add trigger_variables to automation config schema

* Don't print stacktrace when setting up trigger throws

* Make pylint happy

* Add trigger_variables to variables

* Add debug prints, document limited template

* Add tests

* Validate MQTT trigger topic early when possible

* Improve valid_subscribe_topic_template

homeassistant/helpers/script_variables.py

@@ -21,6 +21,7 @@ class ScriptVariables:
         run_variables: Optional[Mapping[str, Any]],
         *,
         render_as_defaults: bool = True,
+        limited: bool = False,
     ) -> Dict[str, Any]:
         """Render script variables.
 
@@ -55,7 +56,9 @@ class ScriptVariables:
             if render_as_defaults and key in rendered_variables:
                 continue
 
-            rendered_variables[key] = template.render_complex(value, rendered_variables)
+            rendered_variables[key] = template.render_complex(
+                value, rendered_variables, limited
+            )
 
         return rendered_variables