apple: Add icons in prep for App Store distribution (#1808)

Adds icons to Apple for app distribution for TestFlight testing.

@pratikvelani -- can these also be used for Android or do we need a
different format? I can add you to our Figma team if you need to slice
the assets directly.

swift/apple/Firezone/Assets.xcassets/AppIcon.appiconset/Contents.json

@@ -1,56 +1,67 @@
 {
   "images" : [
     {
+      "filename" : "logo-1024.png",
       "idiom" : "universal",
       "platform" : "ios",
       "size" : "1024x1024"
     },
     {
+      "filename" : "logo-16.png",
       "idiom" : "mac",
       "scale" : "1x",
       "size" : "16x16"
     },
     {
+      "filename" : "logo-32.png",
       "idiom" : "mac",
       "scale" : "2x",
       "size" : "16x16"
     },
     {
+      "filename" : "logo-32 1.png",
       "idiom" : "mac",
       "scale" : "1x",
       "size" : "32x32"
     },
     {
+      "filename" : "logo-64.png",
       "idiom" : "mac",
       "scale" : "2x",
       "size" : "32x32"
     },
     {
+      "filename" : "logo-128.png",
       "idiom" : "mac",
       "scale" : "1x",
       "size" : "128x128"
     },
     {
+      "filename" : "logo-256.png",
       "idiom" : "mac",
       "scale" : "2x",
       "size" : "128x128"
     },
     {
+      "filename" : "logo-256 1.png",
       "idiom" : "mac",
       "scale" : "1x",
       "size" : "256x256"
     },
     {
+      "filename" : "logo-512.png",
       "idiom" : "mac",
       "scale" : "2x",
       "size" : "256x256"
     },
     {
+      "filename" : "logo-512 1.png",
       "idiom" : "mac",
       "scale" : "1x",
       "size" : "512x512"
     },
     {
+      "filename" : "logo-1024 1.png",
       "idiom" : "mac",
       "scale" : "2x",
       "size" : "512x512"