feat: Benchmarking implementation

[guptaakashdeep]

This includes all the initial changes done for implementing benchmarking for Graph Algorithms using Pregel.

• Python Script for running benchmarks after downloading and extracting LDBC datasets based on dataset name.
• Benchmarking folder setup, inclusion of Criterion in dependencies and bench setup for running benchmarks in cargo.toml
• Benchmarking data won't be pushed in repo, hence added bench/data folder in gitignore.
• LDBC common functions are moved inside a util.rs file so it can be read across the project for testing and benchmarking runs.
• Added a benchmark_run flag in LDBC function to decide whether dataset needs to be picked from benchmarking or testing data folder.
• Updates in other files to accomodate the change.

[SemyonSinchenko]

LGTM! Nice work!