feat(ffi): add cargo-c support (#3787) #2906

Job	Run time
Check Style	4s
semver	20s
Verify hyper.h is up to date	28s
features	38s
Test with Miri	2m 52s
Test C API (FFI)	59s
Test cargo-c support (FFI)	34s
minimal-versions	33s
Check MSRV	48s
udeps	24s
Test stable on ubuntu-latest	1m 17s
Test stable on windows-latest	3m 24s
Test stable on macOS-latest	1m 23s
Test beta on ubuntu-latest	1m 25s
Test beta on windows-latest	2m 16s
Test beta on macOS-latest	1m 34s
Test nightly on ubuntu-latest	1m 20s
Test nightly on windows-latest	2m 26s
Test nightly on macOS-latest	1m 45s
Build docs	20s
Check exposed types	29s
CI is green	1s
	25m 20s

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