Improved Rust py example

[assambar]

Add helper crates for usage of libpython in Rust.

• wlr-libpy - offers methods that download and setup all static lib dependencies necessary for linking with the pre-built libpython from Wasm Language Runtimes in wasm32-wasi modules built in Rust
• wlr-assets - generic download and extract functionality for build assets

Improve the example, which demonstrates how to embed libpython in Rust - `python/examples/embedding/wasm-py-rs

Here is the readme - https://github.com/vmware-labs/webassembly-language-runtimes/tree/rust-py-example/python/examples/embedding/wasi-py-rs`

[ereslibre]

Thank you @assambar! I haven't tested my own suggestions, but the idea is that crates can be referred to locally with path, without the need to pull from GitHub -- what would enforce us to push, or use a cargo override. If we can refer to this dependency crates locally on the filesystem I think it would be great.

LGTM!

[Angelmmiguel]

LGTM! I just added a few minor comments on the different crates. I love to see how easy is to embed now our Python + Wasm build 😄

[Angelmmiguel]

Love this!

[ereslibre]

Thanks @assambar! 👏