Add clap comments, add additional derives to bindings

[mikkelhegn]

A quick fix to add a bunch of derives to the Rust bindings. More work to expose as a flag to the CLI.

Also work to do to add wit-bindgen as a dependency if not there already.

[mikkelhegn]

@karthik2804 FYI - mainly to show what I had to do to make this example work: https://github.com/mikkelhegn/spin-component-examples/tree/spin-components/spin-app-import/spin-app-dependencies

[karthik2804]

I assume the Todos will be handled in a separate PR? or is that still a WIP?

[mikkelhegn]

Hmm - maybe talk about what to do and get it in to this PR would be an option? I'd like to close the loop on adding wit-bindgen. Maybe it's just an output to the console Make sure to add wit-bindgen to your project.?

[karthik2804]

I think just having an output to the console would be fine for now, because we have to otherwise end up parsing where the cargo.toml for that project is and things of that nature.

[mikkelhegn]

Feel free to take it as-is.

[mikkelhegn]

@karthik2804 I don't have merge rights, so it's up to you :-)