Raise Error when using a compound dtype that is not formally defined in the spec or extension.

[mavaylon1]

Using a compound data type without defining an extension is currently not supported. This is to add a check and test to prevent this.

Fix #1265 Original Issue: https://github.com/hdmf-dev/hdmf-zarr/issues/273

Checklist

• [x] Did you update CHANGELOG.md with your changes?
• [x] Does the PR clearly describe the problem and the solution?
• [x] Have you reviewed our Contributing Guide?
• [x] Does the PR use "Fix #XXX" notation to tell GitHub to close the relevant issue numbered XXX when the PR is merged?

[codecov[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 91.70%. Comparing base (a6fd15b) to head (0176eb8). :warning: Report is 6 commits behind head on dev.

Additional details and impacted files

@@           Coverage Diff           @@
##              dev    #1276   +/-   ##
=======================================
  Coverage   91.69%   91.70%           
=======================================
  Files          42       42           
  Lines        9610     9615    +5     
  Branches     1938     1940    +2     
=======================================
+ Hits         8812     8817    +5     
  Misses        519      519           
  Partials      279      279           

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[rly]

Looks good, thanks!