Uncolored clouds and PointNet baseline

[Vynikal]

Uncolored clouds

The motivation is to use the model as an augmentation of FLAIR dataset without using inaccurate cloud colorizing. As the attributes are different, it's necessary to write a new dataset description and pre-transform. Also rgb normalizing is now conditional to to rgb attribute. NoRGB separate experiments were created.

PointNet baseline

Taking advantage of the modular design of Myria3D, just another model to compare with, nothing more, nothing less. Also coming with the NoRGB variant.

The two NoRGB models were trained and tested, more info in the forked repository readme, also including trained checkpoints.

It might not be perfect, feel free to point out the issues.