Limit which lfs assets are pulled by default

[dagardner-nv]

• Adds helper script scripts/fetch_data.py to pull additional assets.
• Update README.md & CONTRIBUTING.md docs to reflect changes
• Updated the hammah unittest to no longer depend on training data.
• Pinned Neo dep to 22.04.00a to work-around incompatible neo version

$ scripts/fetch_data.py -h
usage: Fetches data not included in the repository by default [-h] {fetch,check} ...

optional arguments:
  -h, --help     show this help message and exit

Subcommands:
  valid subcommands

  {fetch,check}
    fetch        Fetch datasets
    check        Check download status of large files. Displays a True/False whether all files are downloaded.

Closes #88

[mdemoret-nv]

Couple of comments. I think the script should be moved to ./scripts filter instead of CI. Also, printing to the console didnt work for me out of the box.

[mdemoret-nv]

The check command is good but needs better output.

[mdemoret-nv]

Looks good. Great addition

[mdemoret-nv]

@gpucibot merge