If we require all annotation item map tools to inherit from
QgsMapToolAdvancedDigitizing, then we lose the flexibility to
subclasss other map tools for annotation item creation (e.g.
QgsMapToolCapture)
when we are editing annotation items, as properties of the item
which aren't exposed in the widget (e.g. it's geometry) may
have changed in the meantime and we don't want to lose those.
This registry is attached to QgsGui and handles registration of
functions which create widgets for modifying QgsAnnotationItems
Modeled heavily off the print layout API
This is the start of a map tool for interactive editing of items
in annotation layers. Currently it supports selecting items, and
pre-highlighting their nodes as the cursor is moved over the items.
(Not exposed in QGIS gui yet)
