Develop Dataset class

[ubdbra001]

closes #30

My initial pass at this. I'm a bit unsure whether passing schema to the Dataset class as a parameter is the best approach, but I didn't want to hardcode the datatypes/modalities either. Thoughts @effigies ?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.06%. Comparing base (079719b) to head (8e37d7c).

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #31      +/-   ##
==========================================
+ Coverage   84.94%   86.06%   +1.11%     
==========================================
  Files          12       12              
  Lines         598      617      +19     
  Branches       95      102       +7     
==========================================
+ Hits          508      531      +23     
+ Misses         69       64       -5     
- Partials       21       22       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[effigies]

+1 to including the schema into the dataset object.