Fix placeholder of textfield

Riot/Modules/Common/Cells/TextFieldTableViewCell.swift

@@ -30,6 +30,7 @@ extension TextFieldTableViewCell: Themable {
     
     func update(theme: Theme) {
         theme.applyStyle(onTextField: textField)
+        textField.placeholderColor = theme.placeholderTextColor
     }
     
 }

Riot/Modules/Common/Views/InsettedTextField.swift

@@ -24,6 +24,26 @@ class InsettedTextField: UITextField {
         }
     }
     
+    var placeholderColor: UIColor? {
+        didSet {
+            updateAttributedPlaceholder()
+        }
+    }
+    
+    override var placeholder: String? {
+        didSet {
+            updateAttributedPlaceholder()
+        }
+    }
+    
+    private func updateAttributedPlaceholder() {
+        guard let placeholder = placeholder else { return }
+        guard let color = placeholderColor else { return }
+        attributedPlaceholder = NSAttributedString(string: placeholder, attributes: [
+            NSAttributedString.Key.foregroundColor: color
+        ])
+    }
+    
     override func placeholderRect(forBounds bounds: CGRect) -> CGRect {
         return bounds.inset(by: insets)
     }