fix: add react-native-test-app specific config conditionally

Author: szymonrybczak

packages/create-react-native-library/templates/native-common-example/example/react-native.config.js

@@ -1,8 +1,11 @@
 const path = require('path');
 const pak = require('../package.json');
+<% if (example === 'test-app') { -%>
 const { configureProjects } = require('react-native-test-app');
+<% } -%>
 
 module.exports = {
+<% if (example === 'test-app') { -%>
   project: configureProjects({
     android: {
       sourceDir: 'android',
@@ -11,6 +14,7 @@ module.exports = {
       sourceDir: 'ios',
     },
   }),
+<% } -%>
   dependencies: {
     [pak.name]: {
       root: path.join(__dirname, '..'),