Customization: MessageButtonStyle
The MessageButtonStyle structure describes the parameters of buttons inside messages
Description of MessageButtonStyle parameters:
- color: UIColor - button background color
- textColor: UIColor - text color
- textFont: UIFont - text font
- cornerRadius: CGFloat - radius of the button corners
- margin: UIEdgeInsets - outer indents of the button
- padding: UIEdgeInsets - indent of the button relative to the button text
