Timebox for investigation: 3 SP

Once a contentType file has an error which causes the app definition to be broken with a severre error, then additional changes to the contentType file will not be detected, and therefore the app will remain broken even once the error in the contentType file is fixed. 

The ContentTypes system should be improved so that even when an app definition has errors, any changes to the referenced contenttype files will be registered and applied - such that the app will work again, as would be expected.

To reproduce

1. Add an app and contenttype definition in a light module.
2. Check in Admincentral that the app is working.
3. Break the contenttype definition, for example by adding a letter 'x' at the top of the file.
4. Check in Admincentral that the app is broken. Note problem in definitions app.
5. Fix the contentType definition.
6. Check in AC that the app is still broken. (Note, problem still in definitions app.)
7. Touch the app file, for example add a space at the end.
8. Check in AC that the app is working again.

Note, there must aldready be some code to apply detected changes to contentTypes files to the apps, as when one makes changes to the CT that are valid, then the app is correctly updated.

You could use these valid files:

App file

https://git.magnolia-cms.com/projects/DEMOS/repos/website-spa-demo/browse/light-modules/spa-website-lm/apps/tours.yaml

CT file 

https://git.magnolia-cms.com/projects/DEMOS/repos/website-spa-demo/browse/light-modules/spa-website-lm/contentTypes/event.yaml