Allow changing target layer when georeferencing

[ChristopherStrong]

It would be nice if there was an option to change the target layer while georeferencing multiple image files.

This functionality exists in ArcMap.  In Pro, in order to change a target layer, a user must hit the Close Georeference button, click on the next layer, and re-open the Georeferencing Toolbar.  (Could this be a bug?)

Since toolbars are dynamic based on the selected layer in ArcGIS Pro, the Target Layer could change when a different layer is selected in the table of contents? 

Or, like ArcMap, perhaps just adding a drop down box to select the Target Layer.

Either would improve the somewhat clunky behavior of closing/re-opening the Georeferencing Toolbar. 

Further, not having this change in Target Layer could mean users inadvertently add control points to the wrong layer (if they don't realize that merely selecting a different layer doesn't update the Target Layer)(Made this mistake myself and undid some work).