Build Acceleration Structure infrastructure for Ray Tracing tests

[MarijnS95]

Smaller tracking issue to document the needed work for Acceleration Structures in the framework.

• Ability to specify acceleration structures (triangles in BLAS, instance(s) of these BLAS(es) in a TLAS) via YAML
• Creating Acceleration Structure objects
• Binding backing buffers to Acceleration Structure objects
  • Includes related buffer usage flags
• Building geometry/instance descriptions from GPU buffers (based on DeviceAddress)
  • Lots of pointer-soup and "keepalive"
  • GPU buffers must allow requesting addresses
• Building geometry/instances into Acceleration Structure objects
  • Requires the new CommandEncoder abstraction to perform this generically across backends
  • Requires proper barrier placement between sequential dependent builds (TLAS must wait for all its BLASes to be built)

Binding these to a ray tracing shader (starting with inline) will be tracked in a separate issue.