feat: add multi-threaded evaluation benchmark suite with comprehensive C# implementation (microsoft#457)

This commit introduces a complete multi-threaded evaluation benchmark suite for both Rust and C# implementations of Regorus.

- Implemented engine evaluation benchmark with input and engine cloning strategies
- Implemented compiled policy evaluation benchmark with input cloning and shared compiled policy strategies.

- Created EngineEvaluationBenchmark.cs and CompiledPolicyEvaluationBenchmark.cs with time-based execution (3s warmup + 3s evaluation)
- Implemented configuration options matching Rust implementation (useClonedEngines, useSharedPolicies parameters)

- Created markdown analysis documentation with cross-platform performance analysis
- C# seems to achieve 58-89% of Rust performance on test machine.

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

Author: anakrish

Cargo.lock

@@ -125,6 +125,8 @@ test-generator = "0.3.1"
 walkdir = "2.3.2"
 criterion = { version = "0.7" }
 
+num_cpus = "1.16"
+
 [build-dependencies]
 anyhow = "1.0"
 
@@ -158,6 +160,16 @@ name = "schema_validation_benchmark"
 harness = false
 required-features = ["azure_policy"]
 
+[[bench]]
+name = "engine_evaluation_benchmark"
+path = "benches/evaluation/engine_evaluation_benchmark.rs"
+harness = false
+
+[[bench]]
+name = "compiled_policy_evaluation_benchmark"
+path = "benches/evaluation/compiled_policy_evaluation_benchmark.rs"
+harness = false
+
 [[example]]
 name="regorus"
 harness=false