Converted PointClouds don't survive a level reload, we should save them as assets?

[JR-Morgan]

When receiving a point cloud in UE, the point cloud will not save in the level, such that reloading the level leads to the pointcloud disappearing.

A solution to this is for our UPointCloudConverter to save the pointcloud as an asset, similar to how we do for StaticMeshes and Materials.

• some commits to test with