Breaking: Adapt coreutils dev file structure V2 #671

Job	Run time
cargo clippy -- -D warnings (macOS-latest)	25s
cargo clippy -- -D warnings (ubuntu-latest)	23s
Code Coverage (ubuntu-latest, unix)	1m 47s
Code Coverage (windows-latest, windows)	4m 50s
cargo fmt --all -- --check	5s
cargo check (ubuntu-latest)	20s
cargo check (macOS-latest)	20s
cargo test (macOS-latest)	57s
cargo clippy -- -D warnings (windows-latest)	57s
cargo check (windows-latest)	1m 6s
GNU test suite	48s
Code Coverage (macos-latest, macos)	2m 22s
cargo test (ubuntu-latest)	38s
cargo test (windows-latest)	1m 41s
	16m 39s

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