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.
`Mods.Common/Traits/Modifiers/` or `Mods.Common/Traits/Render/` for directory?