Deprecate NWBGroupSpec.add_group, add_dataset

[rly]

Motivation

Coordinating with https://github.com/hdmf-dev/hdmf/pull/1333

How to test the behavior?

python test.py

Checklist

• [x] Did you update CHANGELOG.md with your changes?
• [x] Have you checked our Contributing document?
• [x] Have you ensured the PR clearly describes the problem and the solution?
• [x] Is your contribution compliant with our coding style? This can be checked running ruff check . && codespell from the source directory.
• [x] Have you checked to ensure that there aren't other open Pull Requests for the same change?
• [x] Have you included the relevant issue number using "Fix #XXX" notation where XXX is the issue number? By including "Fix #XXX" you allow GitHub to close issue #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 95.24%. Comparing base (4c28a99) to head (150fad4).

Additional details and impacted files

@@           Coverage Diff           @@
##              dev    #2138   +/-   ##
=======================================
  Coverage   95.23%   95.24%           
=======================================
  Files          29       29           
  Lines        2876     2879    +3     
  Branches      740      740           
=======================================
+ Hits         2739     2742    +3     
  Misses         83       83           
  Partials       54       54           

Flag	Coverage Δ
integration	74.40% <33.33%> (-0.05%)	:arrow_down:
unit	84.96% <100.00%> (+0.01%)	:arrow_up:

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