dzn: Use new SM6.8 intrinsics to optimize indirect drawing
SM6.8 adds (finally) start vertex/instance location sysvals. We also added ExecuteIndirect tier 1.1, which is technically independent but more or less part of the same bag of features, which provides a way to get a draw ID. With those, we can remove the need to internally allocate / patch indirect arg buffers, which also means we don't need to break up render passes for indirect drawing.
This is a prereq for landing !23843
This work uncovered a D3D bug where validation in ExecuteIndirect
was too strict. This validation is fixed in the 1.613.2 Agility SDK, so this series also picks up that new package.
Edited by Jesse Natalie