fix: add missing jest-preset.js export (#55618)

Summary:
The new `react-native/jest-preset` package did not include critical `jest-present.js` file in the exported version: https://www.npmjs.com/package/react-native/jest-preset?activeTab=code

Without this the new preset is not usable, and the old preset is no longer available (in nightly versions)

Changelog: [Internal]

Pull Request resolved: #55618

Reviewed By: cortinico

Differential Revision: D93727883

Pulled By: huntie

fbshipit-source-id: b486d3cdd9b1bed7dab7ae70d2c1afcd9dad1083

Author: mdjastrzebski

packages/jest-preset/package.json

@@ -19,6 +19,7 @@
   "main": "./jest-preset.js",
   "files": [
     "jest",
+    "jest-preset.js",
     "index.js",
     "README.md",
     "!**/__docs__/**",