Inject ReproStim-specific bids-inject fields into the BIDS scans.json data dictionary

[vmdocua]

Update or create the scans.json data dictionary in the dataset root.

Tasks:

• Provide -d / --dataset option to explicitly specify the dataset location.
• Create the default scans.json as a resource under assets/bids.
• Change the --dry-run short option from -d to -n.
• Implement logic to create or update scans.json in the current dataset.
• Update tests and documentation.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.83%. Comparing base (63c6446) to head (5773b06).
⚠️ Report is 5 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #272   +/-   ##
=======================================
  Coverage   80.83%   80.83%           
=======================================
  Files          44       44           
  Lines        9011     9011           
  Branches      722      722           
=======================================
  Hits         7284     7284           
  Misses       1643     1643           
  Partials       84       84           

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