JIT

gh-143667: Specialize FOR_ITER for dict.items(), and scalar replace the pair in the JIT #4947

Job	Run time
Interpreter (Debug)	11m 12s
JIT with tail calling interpreter (21)	4m 17s
Free-Threaded (Debug) (21)	16m 58s
JIT without optimizations (Debug) (21)	12m 58s
aarch64-pc-windows-msvc/msvc (Debug)	24m 11s
i686-pc-windows-msvc/msvc (Release)	13m 48s
x86_64-pc-windows-msvc/msvc (Release)	14m 34s
aarch64-apple-darwin/clang (Debug)	12m 21s
aarch64-apple-darwin/clang (Release)	10m 36s
x86_64-pc-windows-msvc/msvc (Debug)	25m 39s
i686-pc-windows-msvc/msvc (Debug)	26m 24s
x86_64-apple-darwin/clang (Debug)	24m 47s
aarch64-pc-windows-msvc/msvc (Release)	18m 39s
x86_64-unknown-linux-gnu/gcc (Release)	8m 25s
aarch64-unknown-linux-gnu/gcc (Debug)	8m 31s
x86_64-apple-darwin/clang (Release)	19m 34s
aarch64-unknown-linux-gnu/gcc (Release)	6m 42s
x86_64-unknown-linux-gnu/gcc (Debug)	13m 9s
	4h 32m 45s

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