Currently, as can be seen in the example here https://git.magnolia-cms.com/projects/PLATFORM/repos/ui/pull-requests/1606/diff#magnolia-ui-framework-jcr/src/test/java/info/magnolia/ui/UploadFieldTest.java?t=115 we need to create an actual yaml-based content app to be able to open a dialog. 

We would want to rather just register a fake app, if any, but the OpenDialogAction does require some UIComponent to work. Fake app however does not have a UIComponent at the moment. 

As part of ticket

• apply the change to the test mentioned above to not be relying on multiValueProperty content app, which is a file created for a different test
• apply the change also to the MultiValuePropertyTest as well and remove the content app afterwards
• apply the change also to the MultiFieldTest as well