Generate force directed graph visualization.

[thayeray]

Problem
For social networks I can set up the network and do the routing in pgRouting, but if I want to see what the network looks like I have to use other tools like Graphviz.

Improvement
Adding a way to generate force directed graph visualizations would improve pgRouting. For example to implement a FDG algorithm that would generate 2d or 3d coordinates for the nodes in the graph.

Alternatives
PostgreSQL has other graph database implementations like Apache AGE but the AGE viewer does not compile fully and the project appears to be abandoned.

[coderabbitai]

A summary of the changes CodeRabbit can apply:

• Add a new "layout" category to pgRouting by adding C++ (C++17/Boost) source files implementing the pgr_fruchtermanReingold algorithm, an SQL wrapper function, documentation and build/install entries so the extension exposes a pgr_fruchtermanReingold(...) call that computes and returns 2D node coordinates (x,y) for storage/visualization (PostGIS export compatible).

• Add an experimental Fruchterman–Reingold force-directed graph layout feature by enabling a new "layout" module in configuration.conf and adding all implementation, driver, C/C++ type headers, SQL wrappers, CMake build entries, examples/results, and documentation: new files created under include/ (coordinate_rt.h, fruchtermanReingold_driver.h), include/layout (fruchtermanReingold.hpp), src/layout (fruchtermanReingold.c, fruchtermanReingold_driver.cpp, CMakeLists.txt), sql/layout (_fruchtermanReingold.sql, fruchtermanReingold.sql, CMakeLists.txt), documentation and examples under doc/layout and docqueries/layout, plus a result sample file and plumbing to return Coordinate_rt results to PostgreSQL.

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