feat: add `copy_*e_to_slice` family #980

Job	Run time
Cargo deny check	19s
Docs	49s
Clippy	50s
Feature checks	1m 31s
Fmt	11s
test (stable, --no-default-features)	1m 40s
test (stable)	1m 39s
test (stable, --all-features)	2m 26s
test (beta, --no-default-features)	1m 44s
test (beta)	1m 43s
test (beta, --all-features)	2m 34s
test (nightly, --no-default-features)	1m 27s
test (nightly)	1m 31s
test (nightly, --all-features)	2m 15s
test (1.65, --no-default-features)	1m 15s
test (1.65)	1m 17s
Accept	1s
	23m 12s

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