chore: remove game_template sample and clean up experimental sample m… (#2829)

Fixes #2526

game_template/macos/Runner/Assets.xcassets/AppIcon.appiconset/Contents.json

@@ -1,68 +0,0 @@
-{
-  "images" : [
-    {
-      "size" : "16x16",
-      "idiom" : "mac",
-      "filename" : "app_icon_16.png",
-      "scale" : "1x"
-    },
-    {
-      "size" : "16x16",
-      "idiom" : "mac",
-      "filename" : "app_icon_32.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "32x32",
-      "idiom" : "mac",
-      "filename" : "app_icon_32.png",
-      "scale" : "1x"
-    },
-    {
-      "size" : "32x32",
-      "idiom" : "mac",
-      "filename" : "app_icon_64.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "128x128",
-      "idiom" : "mac",
-      "filename" : "app_icon_128.png",
-      "scale" : "1x"
-    },
-    {
-      "size" : "128x128",
-      "idiom" : "mac",
-      "filename" : "app_icon_256.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "256x256",
-      "idiom" : "mac",
-      "filename" : "app_icon_256.png",
-      "scale" : "1x"
-    },
-    {
-      "size" : "256x256",
-      "idiom" : "mac",
-      "filename" : "app_icon_512.png",
-      "scale" : "2x"
-    },
-    {
-      "size" : "512x512",
-      "idiom" : "mac",
-      "filename" : "app_icon_512.png",
-      "scale" : "1x"
-    },
-    {
-      "size" : "512x512",
-      "idiom" : "mac",
-      "filename" : "app_icon_1024.png",
-      "scale" : "2x"
-    }
-  ],
-  "info" : {
-    "version" : 1,
-    "author" : "xcode"
-  }
-}