- Arguments are now grouped in a new `PageData` NamedTuple, making it simpler to use, and
easier to extend.
- Page index is automatically calculated, and can be checked in callback to know which
page to show.
- Form send by calling entity is automatically parsed, using original form to instantiate
the right field types.
- A new `DataForm.get_field` method use Generic type as second argument to retrieve the
right field when getting a `submit` form.
- Updated all classes registering Ad-Hoc commands to use the new system and simplify the
code.
This new model is easier to manipulate and serialize, and use the benefits from Pydantic's
data validation mechanisms. It has method to easily convert to/from Wokkel data form or
to/from a domish.Element.
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