Add core namespace to NamespaceCatalog

[stephprince]

Motivation

Fix #2064.

These changes will update the conditions in which the "ignore cached namespaces" warning is displayed and will only warn for core namespaces if the cached version is newer than the loaded version.

After HDMF 4.1.0 is released, this can be fully tested and merged.

How to test the behavior?

from pynwb import NWBHDF5IO

io = NWBHDF5IO("tests/back_compat/2.1.0_nwbfile_with_extension.nwb", "r")
io.read()  # no warnings should be raised

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.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.83%. Comparing base (fef82aa) to head (53fded2).
⚠️ Report is 31 commits behind head on dev.

Additional details and impacted files

@@           Coverage Diff           @@
##              dev    #2077   +/-   ##
=======================================
  Coverage   94.83%   94.83%           
=======================================
  Files          28       28           
  Lines        2751     2751           
  Branches      708      708           
=======================================
  Hits         2609     2609           
  Misses         82       82           
  Partials       60       60           

Flag	Coverage Δ
integration	74.15% <100.00%> (-0.04%)	⬇️
unit	84.84% <100.00%> (ø)

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[stephprince]

@rly this should be ready to review - the test failures should be addressed in #2090, which would ideally be merged first to confirm bumping the HDMF minimum does not cause any other errors.