Refactor: Move advanced graph algorithm demos to the demos module (PR 2)

[Akshatshukla-25]

Description

This PR relocates the interactive advanced graph algorithm demo functions from src/advanced_graph_algorithms into the newly created demos/advanced_graph_algorithms directory.

This keeps the core visualizers and algorithm logic inside src/ while organizing the user-facing demo logic within the demos module.

Resolves

• Resolves Refactor: Decouple consolidated Advanced Graph Algorithm demos into standalone interactive routines #866

Relocated Demo Files

• demos/advanced_graph_algorithms/scc_demo.c
• demos/advanced_graph_algorithms/max_flow_demo.c
• demos/advanced_graph_algorithms/bipartite_matching_demo.c
• demos/advanced_graph_algorithms/eulerian_path_demo.c
• demos/advanced_graph_algorithms/advanced_graph_algorithms_demo.c

Core Changes

• Exposes visualizer functions (visualize_tarjan, visualize_kosaraju, visualize_ford_fulkerson, visualize_edmonds_karp, visualize_dinic) in advanced_graph_algorithms.h and removed static definitions in the source files.
• Updates CMakeLists.txt and Makefile to compile the new demos/advanced_graph_algorithms directory.

Verification & Testing

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