CMS-3285 Make it possible to render component without descriptor
Renamed ComboBox.onValueChanged to onOptionFilterInputValueChanged
Renamed Dropdown.onValueChanged to onOptionFilterInputValueChanged
and created selector.OptionFilterInputValueChangedEvent to be resued by both Combobox and Dropdown
Moved content input types (ImageSelector, Image, Relationship) to the content module.
This made it possible for ContentSummaryLoader to also be moved to content module where it belongs.