Constrain image heights in feeds and threads (#5129)

* Limit height of images within posts

* Add some future-proofness

* Comments, improve a11y

* Adjust ALT, add crop icon

* Fix disableCrop in record-with-media posts

* Clean up aspect ratios, handle very tall images

* Handle record-with-media separately, clarify intent using enums

* Adjust spacing

* Adjust rwm embed image size on mobile

* Only do reduced layout if images embed

* Adjust gap in small embed variant

* Clean up grid layout

* Hide badge on small variant with one image

* Remove crop icon from image grid, leave on single image

* Fix sizing in Firefox

* Fix fullBleed variant

src/components/dms/MessageItemEmbed.tsx

@@ -2,7 +2,7 @@ import React from 'react'
 import {View} from 'react-native'
 import {AppBskyEmbedRecord} from '@atproto/api'
 
-import {PostEmbeds} from '#/view/com/util/post-embeds'
+import {PostEmbeds, PostEmbedViewContext} from '#/view/com/util/post-embeds'
 import {atoms as a, native, useTheme} from '#/alf'
 
 let MessageItemEmbed = ({
@@ -14,7 +14,11 @@ let MessageItemEmbed = ({
 
   return (
     <View style={[a.my_xs, t.atoms.bg, native({flexBasis: 0})]}>
-      <PostEmbeds embed={embed} allowNestedQuotes />
+      <PostEmbeds
+        embed={embed}
+        allowNestedQuotes
+        viewContext={PostEmbedViewContext.Feed}
+      />
     </View>
   )
 }