Add benchmarks of 'write_[u]int[128]' #1576

Job	Run time
miri	1m 25s
rustfmt	10s
test (pinned, ubuntu-latest, 1.60.0)	1m 0s
test (stable, ubuntu-latest, stable)	31s
test (beta, ubuntu-latest, beta)	33s
test (nightly, ubuntu-latest, nightly)	1m 9s
test (macos, macos-latest, stable)	46s
test (win-msvc, windows-latest, stable)	1m 6s
test (win-gnu, windows-latest, stable-x86_64-gnu)	1m 18s
test (stable-x86, ubuntu-latest, stable, i686-unknown-linux-gnu)	49s
test (stable-aarch64, ubuntu-latest, stable, aarch64-unknown-linux-gnu)	52s
test (stable-powerpc64, ubuntu-latest, stable, powerpc64-unknown-linux-gnu)	52s
test (stable-s390x, ubuntu-latest, stable, s390x-unknown-linux-gnu)	56s
	11m 27s

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