[Feature Request] SIMD powered `Dict`

[soraros]

Review Mojo's priorities

• [X] I have read the roadmap and priorities and I believe this request falls within the priorities.

What is your request?

Make Dict a SIMD powered hash map, like for instance absl::flat_hash_map.

What is your motivation for this change?

Great performance is always good. What I find more equally interesting is that Mojo could be the perfect language in which to write such an implementation, and it will serve as an example of Mojo's SIMD capability.

Any other details?

No response