Make `yarn` and `yarn jest react-native-codegen` works on Windows with git (#34854)

Summary:
A few fixings to make `yarn jest react-native-doegen` works on Windows:

- ~~Add a `.gitignore` file to tell git not to track generated/temporary files.~~
- There is no `rm` on Windows, change it to `rimraf`.

I have been using it in the last 3 months and it works perfectly on Windows, otherwise I could not even build the code in my laptop.

## Changelog

[General] [Changed] - Make `yarn` and `yarn jest react-native-codegen` works on Windows with git

Pull Request resolved: https://github.com/facebook/react-native/pull/34854

Test Plan: `yarn jest react-native-codegen` passed

Reviewed By: cortinico

Differential Revision: D40059524

Pulled By: cortinico

fbshipit-source-id: e3cde2506c7d18c2b580099257637b90f4cb328c

packages/react-native-codegen/package.json

@@ -10,7 +10,7 @@
   },
   "scripts": {
     "build": "yarn clean && node scripts/build.js --verbose",
-    "clean": "rm -rf lib",
+    "clean": "rimraf lib",
     "prepare": "yarn run build"
   },
   "license": "MIT",
@@ -38,6 +38,7 @@
     "invariant": "^2.2.4",
     "micromatch": "^4.0.4",
     "mkdirp": "^0.5.1",
-    "prettier": "^2.4.1"
+    "prettier": "^2.4.1",
+    "rimraf": "^3.0.2"
   }
 }

packages/react-native-codegen/src/generators/__tests__/RNCodegen-test.js

@@ -19,6 +19,7 @@ describe('RNCodegen.generate', () => {
   beforeEach(() => {
     jest.resetModules();
   });
+
   it('when type `all`, with default paths', () => {
     jest.mock('fs', () => ({
       existsSync: location => {