7.x islandora 4 multi value fields

[nigelgbanks]

For DGI issue 7.x-ISLANDORA-4 Fix multi-valued fields in Form Builder

https://discoverygarden.atlassian.net/browse/ISLANDORA-4

This doesn't resolve the issue since it's much deeper in the code base, this just prevents users from encountering the bugs.

[nigelgbanks]

Changes make it so you can still use unallowed elements such as 'checkbox', 'checkboxes', 'date', 'file', 'managed_file',
'password_confirm', 'radio', 'radios', 'tableselect', 'vertical_tabs', 'weight', 'button', 'image_button', 'submit'. But the builder will no longer allow you to give XML CRUD actions to these elements, also the 'select' element doesn't allow XML CRUD combined with multiple.