A rust port of beheader

Hi, I made a Rust port of beheader at https://github.com/rightester/beheader-rs. It integrates most of external tool logic into a single binary (only needs ffmpeg), has a lib/bin split for library use, and adds WASM/WASI support. Pre-built binaries are available in the releases. Thought I'd share in case you'd like to link it.