feat: migrate unit tests to Jest (#6353)

* config(jest): updated setup
* config(jest): update testMatch to include jsx files
* config(jest): add transformIgnorePatterns
* config(jest): update ignore files that do not work in jest yet
* config: add test:unit-jest to test script

* fix(jest): lint with eslint-plugin-jest

* refactor(jest): move unit test directory
* refactor(mocha): restore mocha tests that fail in jest

* docs(jest): update helpful scripts with test:unit-jest

config/jest/jest.unit.config.js

@@ -0,0 +1,24 @@
+const path = require('path');
+
+module.exports = {
+  rootDir: path.join(__dirname, '..', '..'),
+  testEnvironment: 'jsdom',
+  testMatch: [
+    '**/test/unit/*.js?(x)',
+    '**/test/unit/**/*.js?(x)',
+  ],
+  // testMatch: ['**/test/unit/core/plugins/auth/actions.js'],
+  setupFilesAfterEnv: ['<rootDir>/test/unit/setup.js'],
+  testPathIgnorePatterns: [
+    '<rootDir>/node_modules/',
+    '<rootDir>/test/build-artifacts/',
+    '<rootDir>/test/mocha',
+    '<rootDir>/test/unit/setup.js',
+    '<rootDir>/test/unit/xss/anchor-target-rel/online-validator-badge.jsx',
+    '<rootDir>/test/unit/components/online-validator-badge.jsx',
+    '<rootDir>/test/unit/components/live-response.jsx',
+  ],
+  transformIgnorePatterns: [
+    '/node_modules/(?!(react-syntax-highlighter)/)'
+  ]
+};