Make `None` compatible with `SupportsBool` protocol #10803

Job	Run time
Test mypyc suite with 32-bit Python	10m 46s
Test suite with py38-ubuntu, mypyc-compiled	23m 27s
Test suite with py38-windows-64	37m 4s
Test suite with py39-ubuntu	26m 31s
Test suite with py310-ubuntu	28m 22s
Test suite with py311-ubuntu, mypyc-compiled	22m 52s
Test suite with py312-ubuntu, mypyc-compiled	35m 42s
mypyc runtime tests with py38-macos	7m 51s
mypyc runtime tests with py38-debug-build-ubuntu	8m 54s
Type check our own code (py38-ubuntu)	2m 7s
Type check our own code (py38-windows-64)	4m 59s
Formatting and code style with Black + ruff	43s
	3h 29m 18s

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