chore: add feature flag for request counting inside Unleash (#6164)

## About the changes

Adds the feature flag for use in request traffic counting

src/lib/__snapshots__/create-config.test.ts.snap

@@ -79,6 +79,7 @@ exports[`should create default config 1`] = `
       "caseInsensitiveInOperators": false,
       "celebrateUnleash": false,
       "changeRequestConflictHandling": false,
+      "collectTrafficDataUsage": false,
       "createdByUserIdDataMigration": false,
       "customRootRolesKillSwitch": false,
       "demo": false,

src/lib/types/experimental.ts

@@ -48,6 +48,7 @@ export type IFlagKey =
     | 'createdByUserIdDataMigration'
     | 'showInactiveUsers'
     | 'inMemoryScheduledChangeRequests'
+    | 'collectTrafficDataUsage'
     | 'useMemoizedActiveTokens';
 
 export type IFlags = Partial<{ [key in IFlagKey]: boolean | Variant }>;
@@ -237,6 +238,10 @@ const flags: IFlags = {
         process.env.UNLEASH_EXPERIMENTAL_IN_MEMORY_SCHEDULED_CHANGE_REQUESTS,
         false,
     ),
+    collectTrafficDataUsage: parseEnvVarBoolean(
+        process.env.UNLEASH_EXPERIMENTAL_COLLECT_TRAFFIC_DATA_USAGE,
+        false,
+    ),
 };
 
 export const defaultExperimentalOptions: IExperimentalOptions = {