Docs: new csv generation for system and benchmark lists

[dyokelson]

Currently the csv files that populate the system and benchmark lists in the docs are generated by iterating through the old directory structure. We need to rewrite the generation scripts and verify that they will work when we remove any old style yaml configs.

Files to update:
https://github.com/LLNL/benchpark/blob/develop/docs/generate-sys-defs-list.py
https://github.com/LLNL/benchpark/blob/develop/docs/generate-benchmark-list.py