chore(rs port): add rustfmt file for consictency and use `cargo fmt`

[fahdfady]

[viferga]

I agree with this, it will be interesting to add fmt and clippy with a standard format either with rs_loader to rs_port. But the current PR is incomplete, I am going to set it up as Draft meanwhile. If you want I can show you how to include this in the build system with CMake so it is run each time on the CI.