Implemented Floyd-Warshall algorithm in the graph module

[ycz1234]

This pull request implements the Floyd-Warshall algorithm in the graph module. The Floyd-Warshall algorithm is used to find the shortest paths between all pairs of vertices in a weighted graph. This implementation provides an efficient way to solve the shortest path problem for all pairs of vertices.

Checklist

• [x] Added description of change
• [x] Added file name matches File name guidelines
• [x] Added documentation so that the program is self-explanatory and educational - Doxygen guidelines
• [x] PR title follows semantic commit guidelines
• [x] Search previous suggestions before making a new one, as yours may be a duplicate.
• [x] I acknowledge that all my contributions will be made under the project's license.

Notes: <Implemented the Floyd-Warshall algorithm to calculate all-pairs shortest paths in a weighted graph.>