Now we have a full list of all possible annotation types and the
numbering corresponds to the order in the specification. Not only is
this more consistent and complete, it also prevents having to add these
constants when a new annotation type is implemented.
Additionally fix an issue where a regular Widget annotation would not
have `data.annotationType` set. It was only set for a
TextWidgetAnnotation, but instead move it to the base Widget annotation
class to add it for all Widget annotations (since TextWidgetAnnotation
inherits from WidgetAnnotation it will have it too).
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