verifyInputItem has visual problems on MultipleSearch

[Macacoazul01]

After adding an illegal item, the text controller isn't cleared on MultipleSearchDropDown and it seems as the item was added.

• Remake MultipleSearchDropDown to put verifyInputItem function inside the widget that holds the overlay list
• Remake SearchDropDown to put verifyInputItem function inside the widget that holds the overlay list
• Clear the text controller on MultipleSearchDropDown