Move flash messages to the left

As the application makes heavy use of right-hand sheets, flash messages
are often lost.

lib/music_library_web/components/layouts/app.html.heex

@@ -152,7 +152,7 @@
     <LiveToast.toast_group
       flash={@flash}
       kinds={[:error, :warning, :info]}
-      corner={:top_right}
+      corner={:top_left}
       connected={assigns[:socket] != nil}
       toasts_sync={assigns[:toasts_sync]}
       toast_class_fn={&toast_class_fn/1}