Cesium Inspector picks the wrong tile with terrain

[IanLilleyT]

Clicking at the red arrow results in the wrong selected tile. This seems to only be a problem when terrain is enabled.

After digging around a little bit, it picks the correct tile after scene.globe.pick in ImageryLayerCollection.prototype.pickImageryLayerFeatures, but somewhere along the way a different tile gets chosen. I didn't look into it too much after that.

[lilleyse]

Fixed in #8567