free: Implement almost all functions of the `free` commands (#35) #80

Job	Run time
cargo clippy -- -D warnings (ubuntu-latest)	18s
Code Coverage (ubuntu-latest, unix)	54s
cargo clippy -- -D warnings (macOS-latest)	34s
cargo fmt --all -- --check	17s
Code Coverage (macos-latest, macos)	38s
cargo check (ubuntu-latest)	17s
cargo clippy -- -D warnings (windows-latest)	40s
Code Coverage (windows-latest, windows)	42s
cargo check (macOS-latest)	37s
cargo test (ubuntu-latest)	30s
cargo check (windows-latest)	43s
cargo test (macOS-latest)	33s
cargo test (windows-latest)	36s
	7m 19s

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