Range query of composite keys

Initially raised by @aklenik on Discord.

> As I see, the functionality of the range query is limited across all chaincode SDKs to simple keys. However, behind the scenes, the range query methods of the SDKs call the same backing function as the partial query functions, which don't have the same limitations. That means that the reason for the limitation is not technical, since a range CAN be queried using composite keys.

> I can't really wrap my head around the why. Using composite keys is the recommended approach for defining structured and robust key spaces. While range query is a strong update-compatible API feature for efficiently traversing well-designed key spaces. The combination of the two is so evident that I was really surprised to see it fail.