Add Error format support, and JSON output option #12370

Job	Run time
Test mypyc suite with 32-bit Python	7m 10s
Test suite with py38-ubuntu, mypyc-compiled	17m 31s
Test suite with py38-windows-64	19m 46s
Test suite with py39-ubuntu	16m 11s
Test suite with py310-ubuntu	15m 12s
Test suite with py311-ubuntu, mypyc-compiled	15m 13s
Test suite with py312-ubuntu, mypyc-compiled	17m 10s
mypyc runtime tests with py39-macos	6m 59s
mypyc runtime tests with py38-debug-build-ubuntu	4m 40s
Type check our own code (py38-ubuntu)	1m 47s
Type check our own code (py38-windows-64)	2m 34s
Formatting and code style with Black + ruff	39s
	2h 4m 52s

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