[ARC] - Improve Message.author reference when running apps in dev mode

[dotchetter]

When running apps in dev mode using pyttman dev app, the Message.author property is a string: "anonymous".

This makes it tedious since apps rely on the Message.author being an object with the id property.

A solution would be, when the Message.author is obviously the dev interacting with the dev shell, to have a mock Author object with the id property as expected with the content "anonymous" or alike.