Made Common namespaces more consistent

This is a follow-up on the decision we've come to in #7036.

A lot of the traits in Common still used old RA-style namespaces. This moves them to Common.Traits.

Additionally, this moves a couple more traits from RA to Common.
I was a bit hesistant due to the name and since it can deal damage. That being said, this trait could have been called ```WithFire``` just as well, so I guess you're right.