The issue was that the API assumed that the `.selection` attribute
was always on either the point domain for points or the stroke domain
for strokes.
Internally the attribute domain depends on the current selection mode.
To fix the issue, the API now checks for the domain of the attribute
and handles it accordingly.
If the selection attribute is on the `'POINT'` domain:
* Reading the `stroke.select` property will check if *any* of the points of
the stroke are selected and return `True` or `False`.
* Writing to the `stroke.select` property will write `True` or `False` to *all* the
points in the stroke.
Also resolves#128645.
Pull Request: https://projects.blender.org/blender/blender/pulls/128687
68c665ffa1