Add `$rolling_*_by()` expressions #842

Job	Run time
build (ubuntu-20.04, x86_64-unknown-linux-gnu)	14m 35s
build (ubuntu-20.04, aarch64-unknown-linux-gnu)	15m 33s
build (macos-14, x86_64-apple-darwin)	24m 6s
build (macos-14, aarch64-apple-darwin)	28m 36s
build (windows-latest, x86_64-pc-windows-gnu)	32m 2s
test (macos-12, release)	2m 48s
test (macos-14, release)	1m 53s
test (windows-latest, oldrel-1)	7m 43s
test (windows-latest, release)	5m 7s
test (ubuntu-latest, oldrel-1)	2m 2s
test (ubuntu-latest, release)	2m 3s
test (ubuntu-latest, devel)	2m 3s
merge	9s
release	0s
	2h 18m 40s

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