facet performance benchmarks

About

These benchmarks measure JSON deserialization and serialization performance across different facet implementations:

• facet-format+jit: Format-agnostic JIT compiler (our main innovation)
• facet-json+jit: JSON-specific JIT using Cranelift
• facet-format: Format-agnostic interpreter
• facet-json: JSON-specific interpreter
• serde_json: Baseline comparison