updated lidar_hd_pre_transform function

[liubigli-tcp]

Hello!

Thank you very much for publishing this framework! It is really amazing!

I have created this pull request to allow any user to work with point clouds that have custom sets of features.
With this commit, the user specifies the list of point cloud features in its dataset_description yaml file.
Let assume that the point clouds in your dataset don't have any color information, the user can simply pass an empty
list in the color_keys and updates the number of input features (d_in) and that's all.

Please let me know if this could be of any interest to you :)

[leavauchier]

Hi @liubigli-tcp
Thanks a lot for your contribution!
It looks interesting to be more flexible on the input file (especially for people who have the possibility to train a new model).
I'll see with the rest of the team to have it intergrated soon