feat(components): add new content-top and content-bottom slots (#3886)

Co-authored-by: Benjamin Canac <canacb1@gmail.com>

src/runtime/components/DropdownMenu.vue

@@ -98,6 +98,8 @@ export type DropdownMenuSlots<
   'item-leading': SlotProps<T>
   'item-label': SlotProps<T>
   'item-trailing': SlotProps<T>
+  'content-top': (props?: {}) => any
+  'content-bottom': (props?: {}) => any
 } & DynamicSlots<MergeTypes<T>, 'leading' | 'label' | 'trailing', { active?: boolean, index: number }>
 
 </script>