This patch adds support for node previews for shader operations, making
node previews fully supported.
The patch was started as an effort to refactor the compositor compiler
to split the shader operators when node previews increase past hardware
limits. However, I realized that the better approach would be to remove
those limits altogether by using texture arrays instead of individual
textures for operation results, then use texture views to slice that
array. This is not implemented in this patch and will require some
prerequisites, namely adding target conversion to GPU texture views as
well as support texture arrays in the DRW texture pool.
Pull Request: https://projects.blender.org/blender/blender/pulls/109250
c2361381cd