Add extra generated checks for attributes

[lawrence-mbf]

Fixes #498

Motivation

See #498

How to test the behavior?

https://github.com/NeurodataWithoutBorders/matnwb/issues/498#issuecomment-1648471569

Checklist

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

[codecov[bot]]

Codecov Report

Merging #518 (ff43b5c) into master (12f1996) will increase coverage by 0.00%. The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #518   +/-   ##
=======================================
  Coverage   87.87%   87.87%           
=======================================
  Files         129      129           
  Lines        5458     5461    +3     
=======================================
+ Hits         4796     4799    +3     
  Misses        662      662           

Files Changed	Coverage Δ
+file/fillExport.m	98.70% <100.00%> (+0.02%)	:arrow_up:

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