Music Player Example - Add E2E tests

[gdorsi]

In order to increase our test coverage and ensure that our example apps are working as expected we want to add an E2E test suite on each example.

For the Music Player Example we want to test the following happy path:

• Create a new user
• The example song should be loaded
• Create a new playlist
• Rename it
• Go back on the "All tracks" and add the example track to the new playlist
• Navigate back to the new playlist
• Verify that the track has been added to the playlist by navigation

For the E2E tests we are using Playwright and the initial setup and the commands can be copied from the pets example.

To enable the CI add "examples/music-player" here.