More detailed visibility control of label extensions

[stoerr]

The creation dialog icon is visible on many fields where it doesn't really belong, such as the 'Author' field, key fields and even the search field that isn't in a dialog.

There is already an attribute aivisibility created in #16 and other commits belonging to #12 which can be added to the widget, e.g.
<cpp:widget type="textfield" label="Author" name="author" value="${model.author}" aivisible="false"/>
but that needs changing Pages and creating a release. As an intermediate solution there are some excluded property names in #12 .

[stoerr]

There is now a configuration based mechanism #33 for AEM that also works for Composum. Since the original plan of changing pages is quite a lot of work and that would amount to creating and maintaining two different mechanisms, I think we should not do this as there is a general solution and there are bigger fish to fry right now.