PipelineLibrary for Ray Tracing

[archimedus]

Pipeline library support for RayTracing pipelines is a major feature that would be nice to have. Introduction of pipeline libraries introduces large change I would like to separate out from RayTracing support itself.

I created pipeline where I started implementation for pipeline libraries: https://github.com/archimedus/amber/tree/amberrt_lib

[archimedus]

Change proposed in https://github.com/google/amber/pull/1039