Introduced LVAC colab notebook.

This notebook contains opensource code for this paper:
Isik et al, "LVAC: Learned Volumetric Attribute Compression for Point Clouds
using Coordinate Based Networks." To appear in Frontiers in Signal Processing.
https://www.frontiersin.org/articles/10.3389/frsip.2022.1008812/

PiperOrigin-RevId: 479449181
Change-Id: Ibf8c2f1354e6ec1a71fa3936946b6b990321eaa2

Author: ssjhv