Remove easy warnings in javafx.controls

- Remove unsupported/unnecessary SuppressWarning annotations
- Remove reduntant type specifications (use diamond operator)
- Remove unused or duplicate imports
- Remove unnecessary casts (type is already correct type or can be autoboxed)
- Remove unnecessary semi-colons (at end of class definitions, or just repeated ones)
- Remove redundant super interfaces (interface that is already inherited)
- Remove unused type parameters
- Remove declared checked exceptions that are never thrown
- Add missing @Override annotations