Example .osl Shaders

Add example .osl shaders to the repo. These could target functionality from the MaterialX project, contain examples from other sources, or a combination of these. The exact location(s), specific content, and accompanying documentation have yet to be determined or created.

The issue does not name any target files, directories, tests, entry points, shader examples, or documentation location. First determine the intended example scope and repository location with the maintainers; done means agreed .osl examples are added with any required accompanying documentation and validation.

Written by the indexing model from the issue text.