Need to be able to set the geolocation of StreetView reality

[blairmacintyre]

The interface argon.configureStage.setStageGeolocation was added to the empty reality, we should add it to the streetview reality.

Also, the streetview reality should not initially default to the current physical location when it is activated, but rather to the location that is being used by the previous Argon reality. So, when I'm in a panorama reality and switch to streetview, it should be a streetview close to that location.

If there streetview has been visible, it should just stay where it last was, of course. But, especially for the cases where we envisioned streetview being useful (e.g., on the desktop, to let someone take an AR experience remotely), it is necessary to control where streetview is.