Add humanoids to Unity dataset processing script.

[0mdc]

Motivation and Context

This adds humanoids to the Unity dataset processing script. GltfSceneConverter doesn't support skinning. Therefore, they are directly copied to the output. A "copy" job type was added to support this, as well as future cases (e.g. assets that are not models).

How Has This Been Tested

Tested output in Unity.

Types of changes

• [Development]

Checklist

• [x] My code follows the code style of this project.
• [x] I have updated the documentation if required.
• [x] I have read the CONTRIBUTING document.
• [x] I have completed my CLA (see CONTRIBUTING)
• [x] I have added tests to cover my changes if required.