[PEP 695] Implement new scoping rules for type parameters #12396

Job	Run time
Test mypyc suite with 32-bit Python	6m 40s
Test suite with py38-ubuntu, mypyc-compiled	6m 39s
Test suite with py38-windows-64	6m 28s
Test suite with py39-ubuntu	6m 39s
Test suite with py310-ubuntu	6m 41s
Test suite with py311-ubuntu, mypyc-compiled	6m 40s
Test suite with py312-ubuntu, mypyc-compiled	6m 37s
mypyc runtime tests with py39-macos	5m 59s
mypyc runtime tests with py38-debug-build-ubuntu	4m 28s
Type check our own code (py38-ubuntu)	1m 56s
Type check our own code (py38-windows-64)	3m 1s
Formatting and code style with Black + ruff	36s
	1h 2m 24s

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