Add ASL functionality as basic module

[TinasheMTapera]

Using https://github.com/PennLINC/aslbids

This functionality should allow users curating ASL data to have a function that:

1. Generates the ASL metadata sidecar using a specified metadata json file
2. Generates the ASL .tsv that accompanies scans automatically from this json

TODO:

• [ ] create a function that replicates https://github.com/PennLINC/aslbids/blob/master/edit_aslbids.py and can produce a json with all of the added data
• [ ] in the heuristic, add a function that parses the metadataextras section using above function
• [ ] in the heuristic, add a function that can write/overwrite a tsv at runtime

@a3sha2

[mflounders]

Let me know if you want to work together on this. I may be able to help and am testing out aslprep with local asl data and utilizing aslbids along the way

[TinasheMTapera]

Totally @mflounders! I am not actively working on this issue at the moment but if you want to pick it up I'm happy to look into it.

[TinasheMTapera]

Done 9ad2123