Identify and fix obsolete data download links check that data downloads work

[bhass-neon]

Python RSDI lessons originally pointed to Citrix file share folders for data. These need to be updated since we no longer have access to that Citrix location. Also clean up typos, etc.

Hyperspectral:

• [ ] hyperspectral_variation_py
• [x] hyperspectral_validation_py

Lidar:

• [x] calc-biomass_py
• [x] classify-chm
• [x] mask-rasters-py