Improve arity error messages with function name and arg count #12

Job	Run time
cross-compile (aarch64-linux-gnu)	2m 48s
cross-compile (x86_64-linux-gnu)	2m 39s
cross-compile (aarch64-macos-none)	2m 42s
cross-compile (x86_64-macos-none)	2m 38s
test-macos	3m 18s
test-linux	2m 49s
	16m 54s

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