Tests

Add Error format support, and JSON output option (#11396) #32

Job	Run time
Test mypyc suite with 32-bit Python	7m 12s
Test suite with py38-ubuntu, mypyc-compiled	17m 16s
Test suite with py38-windows-64	18m 48s
Test suite with py39-ubuntu	16m 18s
Test suite with py310-ubuntu	15m 0s
Test suite with py311-ubuntu, mypyc-compiled	15m 11s
Test suite with py312-ubuntu, mypyc-compiled	17m 11s
mypyc runtime tests with py39-macos	6m 43s
mypyc runtime tests with py38-debug-build-ubuntu	4m 44s
Type check our own code (py38-ubuntu)	1m 49s
Type check our own code (py38-windows-64)	2m 41s
Formatting and code style with Black + ruff	40s
	2h 3m 33s

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