feat: add DecodedProofRetainer #253

Job	Run time
clippy	32s
docs	28s
feature-checks	22s
fmt	12s
miri --no-default-features	4m 29s
test stable --no-default-features	17s
miri	4m 17s
test stable	12s
miri --all-features	4m 48s
test stable --all-features	37s
test beta --no-default-features	37s
test beta	36s
test beta --all-features	47s
test nightly --no-default-features	31s
test nightly	35s
test nightly --all-features	45s
test 1.81 --no-default-features	14s
test 1.81	15s
test 1.81 --all-features	27s
deny / cargo deny check	13s
	21m 14s

Provide feedback