Add Error format support, and JSON output option #12367

Job	Run time
Test mypyc suite with 32-bit Python	7m 9s
Test suite with py38-ubuntu, mypyc-compiled	17m 38s
Test suite with py38-windows-64	19m 47s
Test suite with py39-ubuntu	16m 42s
Test suite with py310-ubuntu	15m 3s
Test suite with py311-ubuntu, mypyc-compiled	14m 21s
Test suite with py312-ubuntu, mypyc-compiled	17m 42s
mypyc runtime tests with py39-macos	4m 20s
mypyc runtime tests with py38-debug-build-ubuntu	4m 32s
Type check our own code (py38-ubuntu)	1m 46s
Type check our own code (py38-windows-64)	2m 22s
Formatting and code style with Black + ruff	47s
	2h 2m 9s

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