refactor: deprecate CORSMiddleware from public interface. #3237

Job	Run time
mypy	1m 33s
validate	13s
pyright	1m 15s
slotscheck	52s
Test server integration (uvicorn<0.27.0)	1m 10s
test-platform-compat	0s
Test server integration (uvicorn>=0.27.0)	1m 7s
Test Minimal Application with Base Dependencies	48s
Test Minimal Pydantic 1 application	1m 2s
test (3.11) / test	1m 58s
test (3.10) / test	2m 10s
test (3.12) / test	3m 35s
test (3.8) / test	3m 11s
test (3.9) / test	2m 19s
build-docs	3m 19s
upload-test-coverage	16s
codeql	2m 39s
sonar	1m 9s
	28m 36s

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