[BE][Spike] Optimise Sbom::PathFinder

From internal discussion -

1. I think we can further improve the performance (of SBOM::PathFinder) by traversing the sbom graph bottom up starting from the target and going up. Right now we are starting from all root nodes to try and reach the target. To achieve this we might have to add extra info about top_level on sbom_graph_path table (emphasis on might!)
2. If we can achieve the point number 1, I think we can also implement the tree iterator algorithm described here to further more improve performance. With some modifications of course.

This spike is to explore on the above two points to try and further optimise the PathFinder.