Add res_multistep sampler from the cosmos code. #464

Job	Run time
test-unix-nightly (macos, 3.11, 12.1, nightly)	10m 26s
test-unix-nightly (linux, 3.11, 12.1, nightly)	6m 24s
test-stable (macos, 3.9, 12.1, stable)	12m 19s
test-stable (macos, 3.10, 12.1, stable)	10m 27s
test-stable (macos, 3.11, 12.1, stable)	10m 48s
test-stable (macos, 3.12, 12.1, stable)	10m 34s
test-stable (linux, 3.9, 12.1, stable)	8m 30s
test-stable (linux, 3.10, 12.1, stable)	6m 50s
test-stable (linux, 3.11, 12.1, stable)	6m 26s
test-stable (linux, 3.12, 12.1, stable)	6m 22s
	1h 29m 6s

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