Add cxxModule to RN-Tester's codegenConfig

Summary:
This introduces the `cxxModule` field for RNTester where the local TM-CXX modules
are specified.

Changelog:
[Internal] [Changed] - Add cxxModule to RN-Tester's codegenConfig

Reviewed By: cipolleschi

Differential Revision: D53669913

fbshipit-source-id: 97b9985b94efe79566d2d06f6081e65fb66478ff

packages/rn-tester/package.json

@@ -37,6 +37,12 @@
     "jsSrcsDir": ".",
     "android": {
       "javaPackageName": "com.facebook.fbreact.specs"
-    }
+    },
+    "cxxModules": [
+      {
+        "name": "NativeCxxModuleExample",
+        "headerPath": "NativeCxxModuleExample.h"
+      }
+    ]
   }
 }