Add O(m+n) Adjacency Lists Sorting Algorithm

[hungz23]

In this pull request, I add an O(m+n) Algorithm for sorting all adjacency lists of a graph G.
It can be useful for some Greedy Algorithm in Graph Theory.

[MridulS]

Thanks for this @hungz23 sorry for the delay in getting this reviewed!

NetworkX has made a bunch of changes in the last 5 years and this function can be now rewritten with just something like

{i: list(G.adj[i]) for i in order}

So if anyone requires this in an implementation of any algorithm they should be able to use this one liner.