- Dialog created similar to the edit dialog of Input field
- On the dialog, the user can edit the list of the drop down field
- This dialog is only for editing of the field, so the user can't select
an item from the list to display in the field.

Change-Id: I6222aba9b211afeb0e9d10d97a49347921ff7353
Reviewed-on: https://gerrit.libreoffice.org/67909
Tested-by: Jenkins
Reviewed-by: Tamás Zolnai <tamas.zolnai@collabora.com>