Submit benchmarks written in Rust to the codebase

[aborg-dev]

This is a followup for #90

Ideally, we would have all Rust benchmarks submitted to wasmtime repository and compiled to WASM as a part of the build process to avoid storing massive WASM binary blobs in Git. This will also make it much easier to experiment with different Rust compilation flags when we try to optimize the resulting zkAsm.

A rough flow will be:

1. We submit a benchmark like https://gist.github.com/akashin/a02b4b72883674072e09b226904f2b5e to wasmtime
2. We introduce a build.rs script that builds it to wasm32 target and stores it in generated directory
3. We pick up the generated WASM file in the test_zkasm.rs and generate zkAsm out of it
4. We run that zkAsm with zkasm_runner.rs

[aborg-dev]

Some relevant resources to learn about Build scripts:

• https://doc.rust-lang.org/cargo/reference/build-scripts.html
• https://web.mit.edu/rust-lang_v1.25/arch/amd64_ubuntu1404/share/doc/rust/html/cargo/reference/build-scripts.html
• https://www.reddit.com/r/rust/comments/14cvubt/statically_embed_the_output_of_a_wasm_crate_in/
• https://kazlauskas.me/entries/writing-proper-buildrs-scripts