[Feature/fmt] Add emmylua_formatter formatting backend

emmylua_analyzer_rust now uses a new formatter: https://github.com/EmmyLuaLs/emmylua-analyzer-rust/tree/0.23.0/crates/emmylua_formatter. @CppCXY is emmylua_formatter meant to be a compatible replacement for EmmyLua CodeStyle, i.e. can we drop CodeStyle from Lux?