blobby: add encode and decode bin utils #1805

Job	Run time
build (1.85.0, wasm32-unknown-unknown)	17s
build (stable, wasm32-unknown-unknown)	9s
build (stable, thumbv7em-none-eabi)	9s
build (1.85.0, thumbv7em-none-eabi)	13s
test (1.85.0)	16s
test (stable)	9s
minimal-versions / minimal-versions	30s
	1m 43s

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