schema translator between a maya directional light and usd distant light

(cherry picked from commit 90ff3f36434d3a82b31ff774278853b8a014a034)

Description (this won't be part of the changelog)

This schema translator demonstrates how a maya directional light convert to a usd distant light and vice versa

These entries will be used to update the changelog.

Use Markdown list syntax for each entry.

Filled out fields will be added to the changelog.

maya directional light import/export

[ ] Make sure the Title and Description of the PR make sense and provide sufficient context for your work
[ ] Do any added files have the correct AL Apache Licence Header?
[ ] Are there Doxygen comments in the headers?
[ ] Are any new features, behaviour changes documented in the .md format documentation?
[ ] Have you added, updated tests to cover new features and behaviour changes?
[ ] Have you filled out at least one changelog entry?