Expose camera position and orientation via LEAP API

The viewer automation framework (LEAP/outleap) currently has no way to query the camera's world-space position or orientation. This data is needed for automated tests that verify camera controls (orbit, pan, zoom, presets) produce correct camera movement.

Proposed solution:
Add a LEAP API endpoint (e.g. under LLViewerControl or a new LLCameraAPI) that returns the camera's current state:

{
  "position": [x, y, z],
  "rotation": [x, y, z, w],
  "fov": 1.0471975
}

This could be a query on an existing API or a new "LLViewerCamera" API with a "getCamera" operation.