Add alt text support and rework image layout (#503)

* Add alt text support and rework image layout

* Add additional BottomSheet implementation to account for nested Composer modal

* Use mobile gallery layout on mobile web

* Missing key

* Fix lint

* Move altimage modal into the standard modal system

* Fix overflow wrapping of images

* Fixes to the alt-image modal

* Remove unnecessary switch

* Restore old imagelayoutgrid code

---------

Co-authored-by: Paul Frazee <pfrazee@gmail.com>

src/state/models/media/gallery.ts

@@ -65,6 +65,10 @@ export class GalleryModel {
     })
   }
 
+  setAltText(image: ImageModel) {
+    image.setAltText()
+  }
+
   crop(image: ImageModel) {
     image.crop()
   }