GitHub Actions workflow to run the tests

[mhdirkse]

No description provided.

[mhdirkse]

This PR introduces a GitHub Actions workflow that runs the Karma tests. In addition, it fixes the strange behavior of running npm run test. The issue was that this command tried to run the tests of both the playground and the library. It first ran the tests of the library and when you tried to exit that, it started the tests of the playground. The command has been updated to be testPlayground. This way it behaves as expected: when you press Ctrl-C in the calling shell it exits properly. You can also close the opened browser window to speed this up.

[Matthbo]

Why add a karma conf file while you could've also added flags to the ng test command?

For example:

{
  "testPlayground": "ng test frank-config-layout-playground --no-watch --browsers=ChromeHeadless"
}

[mhdirkse]

Ik gebruik npm run ng test .... Dan heb je een extra -- separator nodig om de opties voor npm te scheiden van de opties voor ng. Dat had ik niet door. Nu heb ik inderdaad een oplossing zonder angular.json aan te passen en zonder karma.conf.js te introduceren. Bedankt.