cast6

Move `gift` to `gift-cipher` and `speck` to `speck-cipher` #306

Job	Run time
test (1.85.0)	22s
build (1.85.0, wasm32-unknown-unknown)	18s
build (1.85.0, thumbv7em-none-eabi)	17s
minimal-versions / minimal-versions	25s
build (stable, wasm32-unknown-unknown)	22s
build (stable, thumbv7em-none-eabi)	9s
test (stable)	17s
	2m 10s

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