v4: Add and expose prop querying - #478

[CONFIG_SCHEMA] Integrations which implement 'async_setup' or 'setup' must define either 'CONFIG_SCHEMA', 'PLATFORM_SCHEMA' or 'PLATFORM_SCHEMA_BASE'. If the integration has no configuration parameters, can only be set up from platforms or can only be set up from config entries, one of the helpers cv.empty_config_schema, cv.platform_only_config_schema or cv.config_entry_only_config_schema can be used.