Track the correct finalLayout in render graph.
Track the correct finalLayout in render graph.

Had a double-bug where DS_WRITE -> DS_READ would become just DS_WRITE,
but the render_pass.cpp implementation also had a bug where finalLayout
would be DS_OPTIMAL even after a DS_READ_ONLY transition.

This READ_ONLY -> OPTIMAL transition would trigger an external
transition without any clear barrier (ouch!).

Themaister/Granite,Themaister/Granite,Themaister/Granite,Themaister/Granite,Themaister/Granite,Themaister/Granite