Exposes bézier handle data through a new `GreasePencilStrokePointHandle` class on each point, which provides `position`, `type`, and `select` for both `point.handle_left` and `point.handle_right`. Also removes the old separate point attributes: * `handle_left_type`, `handle_right_type` * `select_handle_left`, `select_handle_right` Pull Request: https://projects.blender.org/blender/blender/pulls/137780