Reorganize types a bit

The input types, input impls, and utility types are now all available in
the versioned API. See the change in `comfy_extras/nodes_video.py` for
an example of their usage.

comfy_api/latest/_input/__init__.py

@@ -0,0 +1,10 @@
+from .basic_types import ImageInput, AudioInput, MaskInput, LatentInput
+from .video_types import VideoInput
+
+__all__ = [
+    "ImageInput",
+    "AudioInput",
+    "VideoInput",
+    "MaskInput",
+    "LatentInput",
+]