Add temporal antialiasing to MaterialX Viewer

[jstone-lucasfilm]

The MaterialX Viewer might benefit from a simple implementation of temporal antialiasing, where the camera transform is jittered each frame, and successive frames are blended together.

In the context of the MaterialX Viewer, no dynamic reprojection would need to be used, and the history buffer could simply be cleared when the user moves the camera.

This antialiasing technique might work particularly well in addressing aliasing of under-sampled MaterialX patterns, which commonly appear in comparisons between real-time and offline renders, and could additionally improve the effectiveness of Filtered Importance Sampling in the context of the viewer.

The following are a few resources that may be useful in this implementation:

• https://en.wikipedia.org/wiki/Temporal_anti-aliasing
• https://sugulee.wordpress.com/2021/06/21/temporal-anti-aliasingtaa-tutorial/
• https://bartwronski.com/2014/03/15/temporal-supersampling-and-antialiasing/