OXT 92: Restructure xenclient-oe.git as a meta layer.

This requires https://github.com/OpenXT/openxt/pull/45

There are a million commits here but they were scripted for the most part and are nearly all the same. They can alternatively be crushed down into one huge commit but this approach was easier for me work with as I was rebasing quite a bit early on. This work mirrors the structure that Adam has adopted for his OE upgrade. I'd like to make additional changes but we need a baseline where the two repos have some commonality. The intent is to make working his changes back into xenclient-oe.git easier (thought it's still gonna be a PITA).