add fallback images for pre iOS13

deltachat-ios/Assets.xcassets/ic_checkmark.imageset/Contents.json

@@ -0,0 +1,21 @@
+{
+  "images" : [
+    {
+      "idiom" : "universal",
+      "scale" : "1x"
+    },
+    {
+      "filename" : "checkmark.png",
+      "idiom" : "universal",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "universal",
+      "scale" : "3x"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

deltachat-ios/Assets.xcassets/ic_trash.imageset/Contents.json

@@ -0,0 +1,21 @@
+{
+  "images" : [
+    {
+      "idiom" : "universal",
+      "scale" : "1x"
+    },
+    {
+      "filename" : "trash.png",
+      "idiom" : "universal",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "universal",
+      "scale" : "3x"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

deltachat-ios/Controller/AccountSwitchViewController.swift

@@ -345,7 +345,7 @@ class AccountCell: UITableViewCell {
         if #available(iOS 13.0, *) {
             image = UIImage(systemName: "trash")
         } else {
-            image = UIImage(named: "")
+            image = UIImage(named: "ic_trash")
         }
         stateIndicator.image = image
         stateIndicator.tintColor = .systemRed
@@ -359,7 +359,7 @@ class AccountCell: UITableViewCell {
         if #available(iOS 13.0, *) {
             image = UIImage(systemName: "checkmark")
         } else {
-            image = UIImage(named: "")
+            image = UIImage(named: "ic_checkmark")
         }
         stateIndicator.image = image
         stateIndicator.tintColor = .systemBlue