[stubtest] Test `NamedTuple` definitions with default fields #10664

Job	Run time
Test mypyc suite with 32-bit Python	5m 44s
Test suite with py38-ubuntu, mypyc-compiled	5m 40s
Test suite with py38-windows-64	5m 30s
Test suite with py39-ubuntu	5m 41s
Test suite with py310-ubuntu	5m 42s
Test suite with py311-ubuntu, mypyc-compiled	5m 41s
Test suite with py312-ubuntu, mypyc-compiled	5m 42s
mypyc runtime tests with py38-macos	5m 38s
mypyc runtime tests with py38-debug-build-ubuntu	5m 42s
Type check our own code (py38-ubuntu)	2m 11s
Type check our own code (py38-windows-64)	2m 42s
Formatting and code style with Black + ruff	51s
	56m 44s

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