Previously these used a gizmo to redo the operator however this
complicated having on-screen gizmos to access tools (see T66304).
Replace this with a generic way to make an operator that only has an
execute function into a modal operator.
This is used for smooth and randomize tools.
Unlike operator gestures, this handles storing and resetting the data.
Currently this only handles edit-mode data, however it's can be
extended to other kinds of data.
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