Improvement and fix to view-proj matrix handling

[mvaligursky]

• if renderTarget.flipY was set, we were y-flipping the view-proj matrix. This fix flips the proj matrix instead, and view-proj matrix just uses already flipped proj matrix. This causes proj matrix to be the same as the one used in view-proj matrix calculation.
• added support for projection matrix range adjustment from internally used OpenGL style with depth in -1..1 range, to DirectX format used by WebGPU, with 0..1 range. This fixes othographic camera rendering examples, and also uses full range of depth for perspective camera / shadow maps.
• slight cleanup of matrix evaluation / set up code as well
• also, we don't call Device.clear unless any of the flags are set