Support NWB schema 2.8.0

[rly]

Motivation

NWB schema 2.8.0 will be released this week. This branch tracks PRs that add support for various changes to the schema. When this is ready to merge, it should be merged without squashing in order to keep individual commit/PR history.

Checklist

• Did you update CHANGELOG.md with your changes?
• Have you checked our Contributing document?
• Have you ensured the PR clearly describes the problem and the solution?
• Is your contribution compliant with our coding style? This can be checked running ruff check . && codespell from the source directory.
• Have you checked to ensure that there aren't other open Pull Requests for the same change?
• 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.

[rly]

See pending 2.8.0 release: NeurodataWithoutBorders/nwb-schema#597

TODO:

• After NWB schema 2.8.0 release, update the submodule to point to the 2.8.0 tag

[codecov]

Codecov Report

Attention: Patch coverage is 83.33333% with 2 lines in your changes missing coverage. Please review.

Project coverage is 91.88%. Comparing base (54c655f) to head (8834110).
Report is 1 commits behind head on dev.

Files with missing lines	Patch %	Lines
src/pynwb/ecephys.py	66.66%	0 Missing and 1 partial ⚠️
src/pynwb/image.py	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #2001      +/-   ##
==========================================
- Coverage   92.04%   91.88%   -0.17%     
==========================================
  Files          27       27              
  Lines        2704     2711       +7     
  Branches      705      707       +2     
==========================================
+ Hits         2489     2491       +2     
- Misses        141      144       +3     
- Partials       74       76       +2     

Flag	Coverage Δ
integration	72.85% <66.66%> (-0.08%)	⬇️
unit	82.84% <83.33%> (-0.15%)	⬇️

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