chore: add rust-vs-c benchmark

[thevilledev]

Continues from N-R-K/ChibiHash#2 (comment)

Changes:

• Add original C implementation to the repository
• Add bench and build files to create similar test cases to run them in C and Rust
• Create comparison report

The test cases here aim to test the following, to see if there's major compiler differences:

• Memory access patterns (zeros, ones, alternating, incremental, random)
• Alignment sensitivity: aligned/unaligned memory access
• Size: variations for input data

[thevilledev]

Example results run on a M3 Pro (aarch64):

Based on this single test run smaller input sizes are faster on Rust. Questions:

• Is it better because of Rust is better with stack-friendly allocations?
• Is the memory layout more cache-friendly in Rust?
• Does FFI add extra overhead to the C calls?
• Rust monomorphisation?

Needs more tests and on different architectures.