Sync top/bottom bar disappearance to the scroll (#1855)

* Disable existing code that toggles shell

* Make shell mode a float

* Translate based on the gesture

* Track header and footer heights

* Add web support

* Fix types and cleanup

* Add back isScrolled logic

* Add comments

src/view/com/notifications/Feed.tsx

@@ -162,7 +162,7 @@ export const Feed = observer(function Feed({
           onEndReached={onEndReached}
           onEndReachedThreshold={0.6}
           onScroll={onScroll}
-          scrollEventThrottle={100}
+          scrollEventThrottle={1}
           contentContainerStyle={s.contentContainer}
           // @ts-ignore our .web version only -prf
           desktopFixedHeight