Alt text for gifs (#3876)

* add alt text dialog

* multiline alt text input

* add pressable alt text badge

* rename `ALT: ` to `Alt text: ` to avoid including old bad ones

* reuse alt text reminder

* reuse alt text reminder in gallery

* add alt text reminder in the dialog itself

* autofocus text input

* reorder components to fix tab order

* fix close btn position

src/view/com/util/images/Gallery.tsx

@@ -1,9 +1,10 @@
-import {AppBskyEmbedImages} from '@atproto/api'
 import React, {ComponentProps, FC} from 'react'
-import {StyleSheet, Text, Pressable, View} from 'react-native'
+import {Pressable, StyleSheet, Text, View} from 'react-native'
 import {Image} from 'expo-image'
+import {AppBskyEmbedImages} from '@atproto/api'
 import {msg} from '@lingui/macro'
 import {useLingui} from '@lingui/react'
+
 import {isWeb} from 'platform/detection'
 
 type EventFunction = (index: number) => void