feat: add app icon

Author: ayechan

Example/Example/Assets.xcassets/AppIcon.appiconset/Contents.json

@@ -11,11 +11,13 @@
       "size" : "20x20"
     },
     {
+      "filename" : "app-icon.png",
       "idiom" : "iphone",
       "scale" : "2x",
       "size" : "29x29"
     },
     {
+      "filename" : "app-icon-1.png",
       "idiom" : "iphone",
       "scale" : "3x",
       "size" : "29x29"
@@ -31,11 +33,13 @@
       "size" : "40x40"
     },
     {
+      "filename" : "app-icon copy.png",
       "idiom" : "iphone",
       "scale" : "2x",
       "size" : "60x60"
     },
     {
+      "filename" : "app-icon copy-1.png",
       "idiom" : "iphone",
       "scale" : "3x",
       "size" : "60x60"