[EAK-246] Implement the ability to disable Multifield via "disabled" property / DependsOn action

[smiakchilo]

Consider the following code:

@DialogField(disabled=true)
@MultiField
@DependsOn(action = DependsOnActions.DISABLED, value = "true")
private List<MyClass> myClasses;

Currently, neither disabled=true nor the DependsOn action does not appear to have any effect on the multifield. (Basically seems an Adobe/Granite issue, but anyway affects user experience). Expected result: at minimum, the "Add" button of the multifield is disabled. Ideally, the content of every multifield item is disabled, as ordinary dialog fields appear in similar circumstances. Probably, the expected result is more easily achieved via a DepensOn action. Then we can discuss whether it is appropriate that @DialogField(disabled=true) will result in storing the same DepensOn action under the hood