This is the same as PR sbromberger/LightGraphs.jl#1559  in the old lightgraphs repository.

From substantial benchmarking, this is a significant speedup in most cases and an asymptotic improvement from quadratic to linear for star graphs, with a performance regression of a few percent only in the limit of extremely sparse graphs. Furthermore, it opens up the possibility for future speedups in other functions provided by this package, since it also computes data that can be directly used in those other functions.

This PR does not change the API for the function itself, but it does add a couple of performance and type hint functions that other library types that inherit from AbstractGraphs can optionally overload to improve/tune performance, for example if they store adjacency lists in a linked list and so have different performance characteristics than array representations.