add types for desktopFixedHeight to List (#4356)

* add types for `desktopFixedHeight`

* nit

* accept both `number` and `boolean`

src/view/com/util/List.tsx

@@ -25,6 +25,7 @@ export type ListProps<ItemT> = Omit<
   onRefresh?: () => void
   onItemSeen?: (item: ItemT) => void
   containWeb?: boolean
+  desktopFixedHeight?: number | boolean
   sideBorders?: boolean
   // Web only prop to disable a perf optimization (which would otherwise be on).
   disableContentVisibility?: boolean

src/view/com/util/List.web.tsx

@@ -22,7 +22,7 @@ export type ListProps<ItemT> = Omit<
   refreshing?: boolean
   onRefresh?: () => void
   onItemSeen?: (item: ItemT) => void
-  desktopFixedHeight: any // TODO: Better types.
+  desktopFixedHeight?: number | boolean
   containWeb?: boolean
   sideBorders?: boolean
   disableContentVisibility?: boolean