Blender animation suggestion

I noticed in [blender-cycles-golden.png](https://github.com/KhronosGroup/glTF-Render-Fidelity/blob/main/test/goldens/khronos-AnimatedTriangle/blender-cycles-golden.png) that the animated triangle is not at the start of its animation cycle.

Blender uses a default start frame number of "1", but glTF animations start at time zero (in seconds, not frame numbers). The answer here might be to add some Python commands to the blender render script:

```
bpy.context.scene.frame_start = 0
bpy.context.scene.frame_current = 0
```

This shouldn't alter non-animated glTF examples, and should make the animated ones start at the beginning, like other engines.

Start by locating the Blender render script that produces test/goldens/khronos-AnimatedTriangle/blender-cycles-golden.png and inspect how animation frames are initialized. Verify the animated triangle begins at the start of its cycle, while non-animated glTF examples remain unchanged.

Written by the indexing model from the issue text.