Fix tsconfig.base.json to ensure proper inclusion of source files

Author: TRomesh

packages/optimizely-cms-sdk/tsconfig.base.json

@@ -10,5 +10,6 @@
     "esModuleInterop": false,
     "strict": true,
     "skipLibCheck": true
-  }
+  },
+  "include": ["src/**/*"]
 }