Add key backup banner close image

Riot/Assets/Images.xcassets/KeyBackup/close_banner.imageset/Contents.json

@@ -0,0 +1,23 @@
+{
+  "images" : [
+    {
+      "idiom" : "universal",
+      "filename" : "close_banner.png",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "universal",
+      "filename" : "close_banner@2x.png",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "universal",
+      "filename" : "close_banner@3x.png",
+      "scale" : "3x"
+    }
+  ],
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  }
+}

Riot/Generated/Images.swift

@@ -59,6 +59,7 @@ internal enum Asset {
     internal static let priorityHigh = ImageAsset(name: "priorityHigh")
     internal static let priorityLow = ImageAsset(name: "priorityLow")
     internal static let createRoom = ImageAsset(name: "create_room")
+    internal static let closeBanner = ImageAsset(name: "close_banner")
     internal static let importFilesButton = ImageAsset(name: "import_files_button")
     internal static let revealPasswordButton = ImageAsset(name: "reveal_password_button")
     internal static let shield = ImageAsset(name: "shield")