Fix read for scalar compound dataset

[ehennestad]

Fix #759

Summary

If a scalar (H5S_SCALAR) compound dataset contains booleans or references, currently parsing would not postprocess such values and they would be returned as int8.

While working on this issue, I also realized that MatNWB would not export a compound scalar dataset using HDF5 scalar dataspace, instead it would create a simple dataspace with shape 1.

Looking at PyNWB, the scalar and compound dataset ElectrodeGroup/position is exported using a scalar dataspace.

PR Changes:

• Added a call to io.parseCompound in io.parseDataset for scalar (H5S_SCALAR) dataspace type.
• Added a condition in io.writeCompound to export as scalar (H5S_SCALAR) if NWB dataset shape is scalar.
• Added unittest confirming expected behavior

How to test the behavior?

runtests('tests.unit.io.ScalarCompoundTest/testScalarCompoundIO')

Todo

• Add unittest

Checklist

• Have you ensured the PR description clearly describes the problem and solutions?
• Have you checked to ensure that there aren't other open or previously closed Pull Requests for the same change?
• If this PR fixes an issue, is the first line of the PR description fix #XX where XX is the issue number?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.59%. Comparing base (541db1d) to head (4696a9a).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #761   +/-   ##
=======================================
  Coverage   95.58%   95.59%           
=======================================
  Files         182      182           
  Lines        6366     6380   +14     
=======================================
+ Hits         6085     6099   +14     
  Misses        281      281           

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