Implement STB 34.101.77-2020 `bash` #246

Job	Run time
miri (s390x-unknown-linux-gnu)	1m 2s
test-simd	14s
miri (x86_64-unknown-linux-gnu)	50s
set-msrv / set-msrv	3s
minimal-versions / minimal-versions	39s
test (1.85.0)	14s
test (stable)	19s
build (1.85.0, wasm32-unknown-unknown)	17s
aarch64-sha3 (1.85.0)	38s
build (stable, thumbv7em-none-eabi)	14s
build (1.85.0, thumbv7em-none-eabi)	14s
build (stable, wasm32-unknown-unknown)	13s
aarch64-sha3 (stable)	40s
	5m 37s

Provide feedback