feat: add `copy_*e_to_slice` family #979

Job	Run time
Cargo deny check	23s
Docs	53s
Feature checks	1m 53s
Fmt	11s
Clippy	48s
test (stable, --no-default-features)	1m 41s
test (stable)	1m 39s
test (stable, --all-features)	2m 29s
test (beta, --no-default-features)	1m 44s
test (beta)	1m 43s
test (beta, --all-features)	2m 33s
test (nightly, --no-default-features)	1m 28s
test (nightly)	1m 33s
test (nightly, --all-features)	2m 13s
test (1.65, --no-default-features)	1m 18s
test (1.65)	1m 16s
Accept	1s
	23m 46s

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