Refactor: Expose standalone demo functions for advanced graph algorithms (PR 1)

[Akshatshukla-25]

Description

This PR refactors the consolidated/bundled demo functions inside the advanced_graph_algorithms module. It extracts internal graph input and node selection helpers to implement and expose standalone demo entry points for each individual algorithm.

This sets the stage for PR 2, which will integrate these standalone demos directly into the demos module.

Resolves

Resolves #866

Refactored Algorithms

1. Strongly Connected Components (SCC):
   • Exposes tarjan_scc_demo(void)
   • Exposes kosaraju_scc_demo(void)
2. Maximum Flow:
   • Exposes ford_fulkerson_demo(void)
   • Exposes edmonds_karp_demo(void)
   • Exposes dinic_demo(void)
3. Bipartite Matching:
   • Exposes dinic_bipartite_matching_demo(void)
   • Exposes hopcroft_karp_demo(void)

Verification & Testing

• Successfully compiled using make.
• Ran unit tests with make test and confirmed all existing tests pass without issues.