feat(otterscan): add ots slim block and serialze OperationType to int #3193

Job	Run time
doctest	1m 4s
clippy	35s
feature-checks	3m 13s
no-std	14s
wasm-unknown	49s
test ubuntu-latest stable --no-default-features	1m 21s
wasm-wasi	1m 11s
test ubuntu-latest stable	1m 18s
test ubuntu-latest nightly --no-default-features	1m 10s
test ubuntu-latest nightly	1m 8s
cfg-check	28s
test ubuntu-latest 1.76 --no-default-features	48s
test ubuntu-latest 1.76	1m 8s
docs	56s
test windows-latest stable --no-default-features	4m 35s
test windows-latest stable	4m 32s
fmt	16s
test windows-latest nightly --no-default-features	4m 3s
test windows-latest nightly	4m 3s
test windows-latest 1.76 --no-default-features	3m 12s
test windows-latest 1.76	2m 25s
	38m 29s

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