feat: add BlockConditional (#1846) #5579

Job	Run time
check no_std	20s
feature-checks	3m 46s
doctest	1m 11s
test ubuntu-latest stable --no-default-features	1m 32s
wasm-unknown	53s
test ubuntu-latest stable	1m 32s
wasm-wasi	1m 16s
clippy	37s
test ubuntu-latest stable --all-features	2m 28s
test ubuntu-latest nightly --no-default-features	1m 21s
docs	55s
fmt	12s
test ubuntu-latest nightly	1m 11s
test ubuntu-latest nightly --all-features	2m 3s
test ubuntu-latest 1.81 --no-default-features	38s
test ubuntu-latest 1.81	51s
test windows-latest stable --no-default-features	4m 18s
test windows-latest stable	3m 26s
test windows-latest stable --all-features	4m 44s
test windows-latest nightly --no-default-features	3m 26s
test windows-latest nightly	3m 3s
test windows-latest nightly --all-features	5m 7s
test windows-latest 1.81 --no-default-features	2m 4s
test windows-latest 1.81	2m 40s
deny / cargo deny check	19s
ci success	2s
	49m 55s

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