feat: add Sealed::as_sealed_ref #2289

Job	Run time
docs	57s
clippy	1m 13s
check no_std	45s
features stable	1m 30s
fmt	12s
features stable --all-targets	2m 52s
miri --no-default-features	5m 48s
features nightly	2m 30s
test ubuntu-latest stable --no-default-features	52s
miri	5m 48s
wasm	24s
features nightly --all-targets	3m 43s
test ubuntu-latest stable	54s
miri --all-features	8m 19s
test ubuntu-latest nightly --no-default-features	1m 18s
test ubuntu-latest nightly	1m 13s
test ubuntu-latest 1.81 --no-default-features	35s
test ubuntu-latest 1.81	37s
test windows-latest stable --no-default-features	2m 46s
test windows-latest stable	3m 58s
test windows-latest nightly --no-default-features	2m 56s
test windows-latest nightly	2m 52s
test windows-latest 1.81 --no-default-features	1m 31s
test windows-latest 1.81	1m 23s
test ubuntu-latest 1.81 --features json	38s
test windows-latest 1.81 --features json	1m 17s
test ubuntu-latest nightly --all-features	1m 21s
test windows-latest nightly --all-features	3m 9s
deny / cargo deny check	20s
ci success	4s
	1h 1m 45s

Provide feedback