Improve camera functionality for Bedrock model viewer

[brettfxio]

This change introduces a robust frameCameraOnMesh camera framing mechanism in BabylonSceneManager, adds a corresponding frame_camera_on_mesh Blockly block, puts it in the Scene toolbox category, updates the Bedrock .mcstructure model viewer workspace to default to a perspective camera with auto-framing on load, and adds Playwright tests to ensure functionality works perfectly.

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PR created automatically by Jules for task 7570993783750106784 started by @brettfxio

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