Add option to change camera pan mode

when I want to drag the model with a left click, when the height of the selected point of my mouse is higher than the height of the camera, the model will pan, but when the height of the selected point is lower then the height of the camera, the model will rotate around the center of the earth. This is understandable, but when the camera height and the height of the selected point are very close but less than the height of the selected point, it will cause such a problem. The model rotates too fast around the center of the earth and causes the model to fly away.

The issue names no source file, test, or entry point. Reproduce the left-drag behavior when the camera and selected-point heights are close, then trace the camera pan/rotation handling and define the configurable pan-mode behavior, including a regression check for the model flying away.

Written by the indexing model from the issue text.