Check bindings.rs into repository

[stefnotch]

I tried building Deno, which depends on this library denoland/deno#27535
At which point I ran into

error: failed to run custom build command for `libuv-sys-lite v1.48.2`

Caused by:
  process didn't exit successfully: `C:\Coding\GitHub\Tools\deno\target\debug\build\libuv-sys-lite-b69ec193f23d297d\build-script-build` (exit code: 101)
  --- stderr
  thread 'main' panicked at C:\Users\Stefnotch\.cargo\registry\src\index.crates.io-6f17d22bba15001f\bindgen-0.70.1\lib.rs:622:27:
  Unable to find libclang: "couldn't find any valid shared libraries matching: ['clang.dll', 'libclang.dll'], set the `LIBCLANG_PATH` environment variable to a path where one of these files can be found (invalid: [])"
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

From what I understand, this project depends on bindgen, which in turn depends on clang. Installing extra dependencies on Windows can be quite tricky.

I also noticed that napi-rs does not have a build.rs file, and instead has the generated bindings in the repository. Would it be reasonable for this project to do the same? If yes, I can try to provide a pull request.

System: Windows 10