Add EgWalker (EuroSys'25) to ArtEvalBench

[bastoica]

This issue tracks the effort of adding EgWalker to ArtEvalBench.

We plan to add a slightly truncated version of the original artifact, that instructs the AI agent to compile, build, prepare/recreate the datasets, run the full suite of experiments, and generate results summaries in both json (raw data) and svg (plots) formats. The entire process might take ~20-24h depending on the hardware characteristics of the machine.

We plan to remove any alternative suggestions for obtaining the experimental results, including the make clean; make "one-shot" command the authors mention.