Combined Eval Script (GNN Efficiency/Purity Plots)

See #41 (closed): Desire to have a combined evaluation plotting function to avoid multiple event loops which slows down evaluation process

This combines the three plotting functions: graph_scoring_efficiency, gnn_efficiency_rz and gnn_purity_rz into a single function graph_scoring_efficiency_purity.

It seems to work fine, but before merging we should perhaps discuss if we would want config flags with conditionals to ignore certain parts of the code if certain eval plots are not desired (such as not wanting a pT plot)