fix: add json type to flagDataTypeMap in feature flag factory

Author: dtoxvanilla1991

src/frontend/factories/feature-flag-factory.ts

@@ -7,6 +7,7 @@ export const flagDataTypeMap: Record<KindeFlagTypeCode, KindeFlagTypeValue> = {
   s: "string",
   i: "integer",
   b: "boolean",
+  j: "json",
 };
 
 export const getFlagFactory = (featureFlags: KindeFeatureFlags) => {