Existing `update_bench_incremental.rb` features

[sim642]

• Add bench repo git describe to HTML.
• Incremental execution: incremental.save, patch, incremental.load.
• Comparison of configuration with baseline configuration per benchmark.
• Extract some statistics (vars, evals).
• YAML based configuration.
• Separate Goblint conf file, configurations specification and benchmarks specification.
• Links to benchmark code on GitHub for viewing instead of local pretty printing.

Incomplete since actively developed. To be decided, which we maybe want to exclude.