Switch the base framework from Create React App to Next.JS

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

jest.config.ts

@@ -0,0 +1,24 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import nextJest from 'next/jest'
+
+const createJestConfig = nextJest({
+  // Provide the path to your Next.js app to load next.config.js and .env files in your test environment
+  dir: './',
+})
+
+// Add any custom config to be passed to Jest
+const customJestConfig = {
+  setupFilesAfterEnv: ['<rootDir>/jest.setup.ts'],
+  moduleNameMapper: {
+    // Handle module aliases (this will be automatically configured for you soon)
+    '^@/components/(.*)$': '<rootDir>/components/$1',
+  },
+  testPathIgnorePatterns: ["/node_modules/", "/cypress/"]
+}
+
+// createJestConfig is exported this way to ensure that next/jest can load the Next.js config which is async
+module.exports = createJestConfig(customJestConfig)