schema attributes wrong for path etc.

[samuelcolvin]

@samuelcolvin current implementation causes issues with Path subclasses (same goes for other classes in field_class_to_schema_enum_disabled I presume):

class ConstrainedPath(Path):
    extensions = None

    @classmethod
    def __modify_schema__(cls, schema: dict):
        update_not_none(schema, extensions=cls.extensions)


class ImagePath(ConstrainedPath):
    extensions = ['.jpg']


class Model(BaseModel):
    path: ConstrainedPath  # 'path': {'title': 'Path', 'type': 'string', 'format': 'path'}
    image: ImagePath  # 'image': {'title': 'Image', 'extensions': ['.jpg']}

As you can see, ImagePath loses type and format keys from schema.

Originally posted by @laevilgenius in #1065 (comment)