Allow multiple values as default when datagrid drop-down search field allowMultiselect=true

The addition of the "Allow multi select" to drop-down search fields was great. However the selection of the default value was not updated. I've had client cases where allowing a multi-default-value here would have meant that I could use a single datagrid, instead of a tab-container with 6 pages full of almost identical datagrids.

Example: in the datagrid the user by default wants to see Projects with status A, B, or C, and objects with status D are usually not relevant. But users have to be able to make their own selection based on their specific search.