chore: Add playwright e2e tests for example app

[jontze]

This pull request introduces end-to-end (E2E) testing using Playwright to the project. It includes updates to configuration files, new dependencies, and several new test cases.

E2E Testing Setup and Configuration:

• Added a new E2E job to the GitHub Actions workflow in .github/workflows/test.yaml to run Playwright tests.
• Updated package.json to include Playwright and related dependencies. [1] [2]
• Configured Playwright in playwright.config.ts to run tests on multiple browsers and set up a local dev server.

Code and Configuration Changes:

• Updated .vscode/extensions.json to recommend the Playwright extension for VS Code.
• Modified .eslintrc.json to extend Playwright's recommended ESLint configuration and added specific rules for E2E test files. [1] [2]
• Updated nx.json to include the Playwright plugin configuration.

New E2E Test Cases:

• Added comprehensive Playwright test cases in apps/ng-remote-config-example/e2e/app.spec.ts, apps/ng-remote-config-example/e2e/config-asset.spec.ts, and apps/ng-remote-config-example/e2e/features-asset.spec.ts to validate the application’s functionality, including checking browser tab titles, JSON viewers, and verifying config files. [1] [2] [3]