[Accessibility] Enter/Return to Send

Being able to send messages, without having to move a hand away from the keyboard would place less strain on one's hands, and allow to text more efficiently. Making this optional and implementing an ability to alter the behavior of the return key in the settings wouldn't break existing workflow patterns, where the user expects a new line to be made, and hopefully, it shouldn't be hard to maintain nor implement.

Edit: If doable, toggling that option on would make the button turn blue and say, "Send" for added legibility.

Start by locating the message composer and the settings entry point in the iOS app. Trace how Return currently inserts a new line and how the Send button is rendered; done means an optional setting sends on Return, preserves the existing behavior when disabled, and updates the button label and color when enabled.