Motivation
When users want to restrict their search to certain file types, they should be guided to only select what is existing.
Task
- use the MenuTagMultiselectWidget and show all file types that are supported by mediawiki in the dropdown
- when a file type is selected for which width/height is applicable, show a width and height field
- Have checkboxes above the file type input box which allow users to choose bundled types (e.g. images)
- When the user selects a checkbox, all appropriate file types are added to the input box
- When the user unselects a checkbox, all appropriate file types are deleted from the input box
- When the user deletes one of the appropriate file types, e.g. ".jpg", the corresponding checkbox, e.g. "image" is unselected
