Fix filters, restyle filters page

Signed-off-by: marcin mikołajczak <git@mkljczk.pl>

app/soapbox/features/forms/index.tsx

@@ -160,14 +160,6 @@ export const SimpleForm: React.FC<ISimpleForm> = (props) => {
   );
 };
 
-interface IFieldsGroup {
-  children: React.ReactNode,
-}
-
-export const FieldsGroup: React.FC<IFieldsGroup> = ({ children }) => (
-  <div className='fields-group'>{children}</div>
-);
-
 interface ICheckbox {
   label?: React.ReactNode,
   hint?: React.ReactNode,