Make identifying Artificial Properties single-values per default

If a property value contains a comma, which is the default separator for list items, then a user may take advantage of the is-single-value control to specify that this value is required to be taken as a single value.

The user has not this control over artificial properties, like the Title.

We need to make the Title and the identifying artificial properties single values per default. This includes, for instance, projectdoc.doctype.common.name, but not Name. For Name the user has control over how to interpret the value and we do not want to interfere with existing use cases.