Improve image viewer (#1843)

This commit does 3 things:
1. Replaces PhotoView (which is abandonware) with modern TouchImageView
2. Fixes an issue with panning images. Gesture was not intercepted
properly and pager was taking control instead of image being moved.
3. Adds feedback to dismissing of images with vertical gesture.

app/src/main/java/com/keylesspalace/tusky/components/compose/dialog/CaptionDialog.kt

@@ -33,9 +33,9 @@ import at.connyduck.sparkbutton.helpers.Utils
 import com.bumptech.glide.Glide
 import com.bumptech.glide.request.target.CustomTarget
 import com.bumptech.glide.request.transition.Transition
-import com.github.chrisbanes.photoview.PhotoView
 import com.keylesspalace.tusky.R
 import com.keylesspalace.tusky.util.withLifecycleContext
+import com.ortiz.touchview.TouchImageView
 
 // https://github.com/tootsuite/mastodon/blob/1656663/app/models/media_attachment.rb#L94
 private const val MEDIA_DESCRIPTION_CHARACTER_LIMIT = 420
@@ -50,9 +50,8 @@ fun <T> T.makeCaptionDialog(existingDescription: String?,
     dialogLayout.setPadding(padding, padding, padding, padding)
 
     dialogLayout.orientation = LinearLayout.VERTICAL
-    val imageView = PhotoView(this).apply {
-        // If it seems a lot, try opening an image of A4 format or similar
-        maximumScale = 6.0f
+    val imageView = TouchImageView(this).apply {
+        maxZoom = 6f
     }
 
     val displayMetrics = DisplayMetrics()