C++: Add feature flag for TRAP caching.

Author: sashabu

lib/feature-flags.js

@@ -46,6 +46,7 @@ export interface FeatureEnablement {
 export enum Feature {
   CodeqlJavaLombokEnabled = "codeql_java_lombok_enabled",
   CppDependencyInstallation = "cpp_dependency_installation_enabled",
+  CppTrapCachingEnabled = "cpp_trap_caching_enabled",
   DisableKotlinAnalysisEnabled = "disable_kotlin_analysis_enabled",
   DisablePythonDependencyInstallationEnabled = "disable_python_dependency_installation_enabled",
   PythonDefaultIsToSkipDependencyInstallationEnabled = "python_default_is_to_skip_dependency_installation_enabled",
@@ -68,6 +69,11 @@ export const featureConfig: Record<
     minimumVersion: "2.15.0",
     defaultValue: false,
   },
+  [Feature.CppTrapCachingEnabled]: {
+    envVar: "CODEQL_CPP_TRAP_CACHING",
+    minimumVersion: undefined,
+    defaultValue: false,
+  },
   [Feature.DisableKotlinAnalysisEnabled]: {
     envVar: "CODEQL_DISABLE_KOTLIN_ANALYSIS",
     minimumVersion: undefined,