Make dyntab expandable

[bendichter]

Motivation

https://github.com/hdmf-dev/hdmf/pull/1013#issuecomment-1852319740

[codecov[bot]]

Codecov Report

Attention: 7 lines in your changes are missing coverage. Please review.

Comparison is base (41fabd4) 88.57% compared to head (5bf6fc5) 88.51%.

Files	Patch %	Lines
src/hdmf/common/table.py	30.00%	7 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #1017      +/-   ##
==========================================
- Coverage   88.57%   88.51%   -0.07%     
==========================================
  Files          45       45              
  Lines        9509     9519      +10     
  Branches     2704     2706       +2     
==========================================
+ Hits         8423     8426       +3     
- Misses        764      771       +7     
  Partials      322      322              

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