Fix multiple nested list widgets

While testing for another issue I found some problems with creating and editing info in nested arrays.

In the attached Studio Jar there is a ComplexFile document type. It uses a modified version of the ComplexTest schema from nuxeo-opencmis.

The attached zip is a core io archive containing a test document. Import the document and verify that the ArrayProp values in the second listItem are all unique. Then edit the document and add or change an entry. Save the document and inspect the ArrayProp values in the second listItem – they will all be identical.

Try also to create a ComplexFile. Add one listItem and enter three values into ArrayProp. Then add another listItem and enter three values into its ArrayProp. You will notice that the ArrayProps will be pre-populated with what was entered in the first listItem. Change them or keep them, doesn't matter. Create the document, and inspect. The three ArrayProp entries on the second list item will be empty.