[VP] Refine folder layout for mhw_render

Refactor on mhw_render for removal of ELG legacy code dependency.
1. rename related class to MhwRenderInterfaceGxx_x, e.g. MhwRenderInterfaceG12_5_Plus
2. Add MhwRenderInterfaceG12_5_Plus class which is base on MhwRenderInterfaceG12 and derived by MhwRenderInterfaceG12_5.
10 files changed