Add GitHub annotations format for `--output` #13159

Job	Run time
Test suite with Python nightly	14m 9s
Test mypyc suite with 32-bit Python	6m 48s
Test suite with py38-ubuntu, mypyc-compiled	17m 55s
Test suite with py38-windows-64	20m 43s
Test suite with py39-ubuntu	19m 10s
Test suite with py310-ubuntu	17m 8s
Test suite with py311-ubuntu, mypyc-compiled	15m 56s
Test suite with py312-ubuntu, mypyc-compiled	18m 13s
mypyc runtime tests with py39-macos	4m 39s
mypyc runtime tests with py38-debug-build-ubuntu	4m 20s
Type check our own code (py38-ubuntu)	1m 48s
Type check our own code (py38-windows-64)	2m 16s
Formatting and code style with Black + ruff	38s
	2h 23m 43s

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