Using the locals parameter makes it so that the code of a Python script runs as
if it were in the body of a ``class``. One effect of this is that functions
defined as part of a script cannot call one another directly.
Fixes: #24704, #13653
* Load user-provided descriptions for python_scripts
* Import SERVICE_DESCRIPTION_CACHE
* Use async_set_service_schema to register service descriptions
* Add python_script tests for loading service descriptions
* Use async/await in test
Paulus Schoutsen
Franck Nijhof
Louis-Dominique Dubeau
Bas Nijholt
Jeff Irion
Paulus Schoutsen