Add Rust code benchmarks

[tholop]

Description

Set up a standard benchmarking process for the Rust primitives. I'm not sure what would be best for us:

• Standard Rust benchmarks
• Criterion?

Type of Test

Performance test (benchmark)

• Keygen/Eval
  • For DPF and DIF
  • For single keys and for batches of keys
• PRG

Note: it can be interesting to set up some profiling too if it is not intrusive (e.g. with Flame).

Expected Behavior

At least a few benchmarks that are easy to trigger (e.g. cargo bench), ideally integrated as a Github workflow.
We can extend the coverage later 🙂

[nph4rd]

I think this can be closed via #32 right @tholop?

[tholop]

Yes, thanks @arturomf94!