Create tool for attributing qor metrics back to source code

This tool would aggregate qor metrics by source function and visualize it some way. A flame graph might be a natural way of presenting this as it is commonly used to show execution time attributed to functions in a call stack.

XLS has a mechanism for attributing IR nodes back to source location. However it is limited and isn't well tested. One limitation is that each node can only be attributed to a single source location. However, optimizations may combine nodes with different source locations so information is lost during optimization. Also, we need to capture call stack location to distinguish different inlined versions of the same function. A node attributed to multiple call stack locations also presents a challenge because we don't want to double count the qor metric at these different call stack locations.