use same border color for all custom UI elements, adapt inputbar's border color on light mode / dark mode change

deltachat-ios/Chat/ChatViewController.swift

@@ -736,6 +736,7 @@ class ChatViewController: UITableViewController {
     
     override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
         scrollDownButton.layer.borderColor = DcColors.colorDisabled.cgColor
+        messageInputBar.inputTextView.layer.borderColor = DcColors.colorDisabled.cgColor
     }
 
     func configureMessageStyle(for message: DcMsg, at indexPath: IndexPath) -> UIRectCorner {
@@ -931,8 +932,7 @@ class ChatViewController: UITableViewController {
         messageInputBar.inputTextView.placeholderTextColor = DcColors.placeholderColor
         messageInputBar.inputTextView.textContainerInset = UIEdgeInsets(top: 8, left: 16, bottom: 8, right: 38)
         messageInputBar.inputTextView.placeholderLabelInsets = UIEdgeInsets(top: 8, left: 20, bottom: 8, right: 38)
-        messageInputBar.inputTextView.layer.borderColor = UIColor.themeColor(light: UIColor(red: 200 / 255, green: 200 / 255, blue: 200 / 255, alpha: 1),
-                                                                             dark: UIColor(red: 55 / 255, green: 55/255, blue: 55/255, alpha: 1)).cgColor
+        messageInputBar.inputTextView.layer.borderColor = DcColors.colorDisabled.cgColor
         messageInputBar.inputTextView.layer.borderWidth = 1.0
         messageInputBar.inputTextView.layer.cornerRadius = 13.0
         messageInputBar.inputTextView.layer.masksToBounds = true