Make mapv_into_any() work for ArcArray, resolves #1280 #314

Job	Run time
docs/stable	20s
cargo-careful	1m 50s
cross_test/s390x-unknown-linux-gnu/stable	5m 2s
clippy/stable	17s
format/nightly	12s
cross_test/i686-unknown-linux-gnu/stable	1m 35s
nostd/thumbv6m-none-eabi/stable	15s
tests/stable	2m 48s
tests/beta	2m 57s
tests/nightly	3m 1s
tests/1.64.0	3m 52s
conclusion	1s
	22m 10s

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