feat: add support for A1111 metadata schema

https://github.com/AUTOMATIC1111/stable-diffusion-webui/blob/cf2772fab0af5573da775e7437e6acdca424f26e/modules/processing.py#L672

modules/config.py

@@ -320,6 +320,11 @@ default_save_metadata_to_images = get_config_item_or_set_default(
     default_value=False,
     validator=lambda x: isinstance(x, bool)
 )
+default_metadata_schema = get_config_item_or_set_default(
+    key='default_metadata_schema',
+    default_value='fooocus',
+    validator=lambda x: x in [y[1] for y in modules.flags.metadata_schema if y[1] == x]
+)
 
 example_inpaint_prompts = [[x] for x in example_inpaint_prompts]