Lauch event on new message read.

When I was working on an outlook web add-in, I was trying to read all the URLs in a message read surface. I was trying to make it seamless buy looking for URLs when the message was first opened (onLoad, onNewMessageRead), but there was no such events.

My idea is simple, add new events for messageReads add-in, like an on onNewMessageRead so that we can implement seamless functionalities.