Add `wb_range_finder_get_point_cloud`

[lukicdarkoo]

We should add an API function that returns a point cloud from RangeFinder.

Reasons:

• actual devices return a point cloud (e.g. RealSense),
• we needed it in our internal projects, and
• we have received a few requests already (e.g. https://github.com/cyberbotics/webots_ros2/issues/227 and a few others on Discord)