Implement STB 34.101.77-2020 `bash` #237

Job	Run time
test-simd	15s
miri (x86_64-unknown-linux-gnu)	46s
miri (s390x-unknown-linux-gnu)	1m 1s
minimal-versions / minimal-versions	30s
set-msrv / set-msrv	3s
aarch64-sha3 (stable)	52s
test (1.85.0)	17s
build (1.85.0, thumbv7em-none-eabi)	14s
build (stable, thumbv7em-none-eabi)	13s
aarch64-sha3 (1.85.0)	42s
build (1.85.0, wasm32-unknown-unknown)	15s
build (stable, wasm32-unknown-unknown)	21s
test (stable)	34s
	6m 3s

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