feat!: add cooperative execution-time limits across engine, VM, and binding (#539)

- Introduce ExecutionTimer/ExecutionTimerConfig to allow limiting evaluating time.
- To amortize time checking costs, checking interval can be configured via the notion of work units
- A global fallback time limit can be set to universally limit all evaluation in addition to engine level limit setting.
- Implement limnits in interpreter and RVM. In RVM, also handle suspend/resume so that time during pause is not counted.
- Add engine-level APIs to set/clear per-engine timer configuration and apply global fallback defaults.
- Surface execution-time limits through FFI and C# bindings
- Add C# tests and example usage to validate engine overrides, global fallback behavior, and compiled policy enforcement.
- Expand docs for execution-time limit
- Add interpreter YAML cases and VM unit tests for time-limit behavior and deterministic time sources.

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

bindings/csharp/Regorus/CompiledPolicy.cs

@@ -203,5 +203,14 @@ namespace Regorus
                 }
             }
         }
+
+        private void UseHandle(Action<IntPtr> action)
+        {
+            UseHandle<object?>(handlePtr =>
+            {
+                action(handlePtr);
+                return null;
+            });
+        }
     }
 }