[change] Remove jest preset

Also add node-based unit tests for SSR APIs.

packages/react-native-web/jest-preset.js

@@ -1,7 +0,0 @@
-module.exports = {
-  moduleNameMapper: {
-    '^react-native$': require.resolve('./dist/cjs')
-  },
-  setupFiles: [require.resolve('./jest/setup.js')],
-  testEnvironment: require.resolve('jest-environment-jsdom')
-};

packages/react-native-web/jest/setup.js

@@ -1,18 +0,0 @@
-/* eslint-env jasmine, jest */
-
-'use strict';
-
-global.__DEV__ = true;
-
-const mockEmptyObject = {};
-
-// Make sure snapshots contain the original style objects
-jest.mock('../dist/cjs/exports/StyleSheet/ReactNativePropRegistry', () => ({
-  register: (id) => id,
-  getByID: () => mockEmptyObject
-}));
-
-jest.mock('../dist/exports/StyleSheet/ReactNativePropRegistry', () => ({
-  register: (id) => id,
-  getByID: () => mockEmptyObject
-}));