feat: language agnostic rust codegen

[eliassjogreen]

⚠️ WIP! ⚠️

This PR addresses #43, #4, #23 by implementing a new codegen in rust which in turn will be used by the macro and in the future extensions to deno bindgen which could enable for example c header support.

Todo:

• [ ] Make the macro use the codegen crate
• [ ] Update the CLI (it will have to be converted to rust to use the new codegen)
• [x] Library loader
  • [x] Deno
  • [x] Plug
• [x] Function generation
• [ ] Into
  • [x] Primitives
  • [x] Pointers
  • [x] Buffers
  • [x] CString
  • [x] Type aliases
  • [x] Structs
  • [x] Tuples
  • [ ] Enums
  • [ ] Arrays
• [ ] From
  • [x] Primitives
  • [x] Pointers
  • [x] Buffers
  • [x] CString
  • [x] Type aliases
  • [x] Structs
  • [x] Tuples
  • [ ] Enums
  • [ ] Arrays
• [ ] JSON/serde fallback?
• [x] Packed structs?
• [ ] Automatic minification and or formatting?
• [ ] Flexible array members?

Previous works, references and resources:

• https://github.com/rustwasm/wasm-bindgen
• https://doc.rust-lang.org/nomicon/other-reprs.html
• https://github.com/rust-lang/rfcs/blob/master/text/2195-really-tagged-unions.md
• https://github.com/sunshine-protocol/dart-bindgen
• https://github.com/dart-lang/ffigen
• https://github.com/denosaurs/plug
• https://github.com/rust-lang/rust-bindgen
• https://github.com/eqrion/cbindgen
• https://github.com/infinyon/node-bindgen

[littledivy]

@eliassjogreen maybe the new CLI should be a custom cargo subcommand? https://github.com/rust-lang/cargo/wiki/Third-party-cargo-subcommands I want to avoid distributing native binaries.

[eliassjogreen]

@littledivy Yep I agree, that sounds like a wise choice

[littledivy]

Closing because stale and merge conflicts.