Move jest config from package.json to dedicated jest.config.js file (f…

…acebook#35856)

Summary:
According to: https://jestjs.io/docs/configuration

> It is recommended to define the configuration in a dedicated JavaScript, TypeScript or JSON file. The file will be discovered automatically, if it is named jest.config.js|ts|mjs|cjs|json.

react-native projects have the jest config in package.json, this change aims to follow jest recommendations and have a dedicated file for jest configs.

Originally suggested here: react-native-community/discussions-and-proposals#583

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[GENERAL] [CHANGED] - Moved jest config from package.json to dedicated jest.config.js file

Pull Request resolved: facebook#35856

Test Plan:
1. cd template
2. yarn
3. yarn test

The test should (still) pass

Reviewed By: christophpurrer

Differential Revision: D42544351

Pulled By: robhogan

fbshipit-source-id: e27d1dad2b52d757777c40a77d0639f381557c88

template/jest.config.js

@@ -0,0 +1,3 @@
+module.exports = {
+  preset: 'react-native',
+};

template/package.json

@@ -29,8 +29,5 @@
     "prettier": "^2.4.1",
     "react-test-renderer": "18.2.0",
     "typescript": "4.8.4"
-  },
-  "jest": {
-    "preset": "react-native"
   }
 }