convert delete gradient/color queryboxes to .ui

Conflicts:
	cui/UIConfig_cui.mk

Change-Id: Ie45c1c0d549fc879043d7f108f33e67adc4721fd
Reviewed-on: https://gerrit.libreoffice.org/6729
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>