feat(nodes): add invocation schema customisation, add model selection

- add invocation schema customisation

done via fastapi's `Config` class and `schema_extra`. when using `Config`, inherit from `InvocationConfig` to get type hints.

where it makes sense - like for all math invocations - define a `MathInvocationConfig` class and have all invocations inherit from it.

this customisation can provide any arbitrary additional data to the UI. currently it provides tags and field type hints.

this is necessary for `model` type fields, which are actually string fields. without something like this, we can't reliably differentiate  `model` fields from normal `string` fields.

can also be used for future field types.

all invocations now have tags, and all `model` fields have ui type hints.

- fix model handling for invocations

added a helper to fall back to the default model if an invalid model name is chosen. model names in graphs now work.

- fix latents progress callback

noticed this wasn't correct while working on everything else.

invokeai/app/invocations/cv.py

@@ -5,14 +5,27 @@ from typing import Literal
 import cv2 as cv
 import numpy
 from PIL import Image, ImageOps
-from pydantic import Field
+from pydantic import BaseModel, Field
+from invokeai.app.invocations.models.config import InvocationConfig
 
 from invokeai.app.models.image import ImageField, ImageType
 from .baseinvocation import BaseInvocation, InvocationContext
 from .image import ImageOutput
 
 
-class CvInpaintInvocation(BaseInvocation):
+class CVInvocation(BaseModel):
+    """Helper class to provide all OpenCV invocations with additional config"""
+
+    # Schema customisation
+    class Config(InvocationConfig):
+        schema_extra = {
+            "ui": {
+                "tags": ["cv", "image"],
+            },
+        }
+
+
+class CvInpaintInvocation(BaseInvocation, CVInvocation):
     """Simple inpaint using opencv."""
     #fmt: off
     type: Literal["cv_inpaint"] = "cv_inpaint"