Display dict of namedtuples

[yoshibase]

Summary

Fixes #230

Fix

When Fire is invoked on a dict whose values are namedtuples, print all entries inline (like dict-of-dicts) instead of showing a help screen.

Tests

cd ../_upstream && python3 -m unittest fire.core_test.CoreTest.testPrintDictOfNamedTuples -v

Test plan

• Local tests pass (see README in staging folder)

[google-cla]

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[yoshibase]

Pausing this PR for now: the cla/google check requires signing Google's CLA, and our contributor policy currently excludes repositories that require CLA signing. The fix remains prepared locally and can be resubmitted once CLA signing is feasible. Thank you for understanding.