[Lightbox] New dismiss gesture (#6135)

* Make iOS scrollview bounded to the image

I've had to remove the dismiss handling because the scroll view no longer scrolls at rest.

* Fix double-tap not working right after a vertical swipe

It seems like for some reason the vertical swipe is still being handled by the scroll view, so double tap gets eaten while it's "coming back". But you don't really see it moving. Weird.

* Add an intermediate LightboxImage component

* Hoist useImageDimensions up

* Implement xplat dismiss gesture

This is now shared between platforms, letting us animate the backdrop and add a consistent "fly away" behavior.

* Optimize Android compositing perf

* Fix supertall images

For example, https://bsky.app/profile/schlagteslinks.bsky.social/post/3l7y4l6yur72e

* Fix oopsie

src/view/com/lightbox/ImageViewing/components/ImageItem/ImageItem.tsx

@@ -1,10 +1,11 @@
 // default implementation fallback for web
 
 import React from 'react'
-import {View} from 'react-native'
+import {ImageStyle, StyleProp, View} from 'react-native'
+import {PanGesture} from 'react-native-gesture-handler'
 import {AnimatedRef} from 'react-native-reanimated'
 
-import {ImageSource} from '../../@types'
+import {Dimensions as ImageDimensions, ImageSource} from '../../@types'
 
 type Props = {
   imageSrc: ImageSource
@@ -14,6 +15,10 @@ type Props = {
   isScrollViewBeingDragged: boolean
   showControls: boolean
   safeAreaRef: AnimatedRef<View>
+  imageAspect: number | undefined
+  imageDimensions: ImageDimensions | undefined
+  imageStyle: StyleProp<ImageStyle>
+  dismissSwipePan: PanGesture
 }
 
 const ImageItem = (_props: Props) => {