Add a helper macro for parsing firefly.toml into Rust helper methods and types

[oli-obk]

I duplicated the toml data structures (they also exist in firefly-cli). While I think long term it would be good to deduplicate them, I didn't know whether/how you'd want that to be done, so I started out this way.

cheats produce a Cheat enum with a variant per cheat. The intended use case is

#[unsafe(no_mangle)]
extern "C" fn cheat(cmd: i32, val: i32) -> i32 {
    match Cheats::from_id(cmd) {
        Cheats::goto_level => {
    }
}

boards and badges produce a module with a method per board/badge. You can invoke them with boards::board_name(peer, score) or badges::the_badge(peer) to set them. If the badge's steps are not set (or 1), then there is no second argument for the badge function. Otherwise there is an argument for setting the progress.

I added unit tests, which both test that the resulting code compiles and show what the code looks like. It is ugly, but no one ever sees it (tho I could run rustfmt on it if you want). This causes a funny cyclic dependency where firefly-rust can depend on firefly-toml, whose tests again depend on firefly-rust

[orsinium]

Thank you! Moved to a separate crate:

https://github.com/firefly-zero/firefly-toml