Do Not Try To Install Benchmark Dependencies If Already Done

Currently we install each benchmark's requirements every time we run the benchmarks, which adds to the time it takes. If we know they are already installed then we can skip that.

Possible solutions:

• only install requirements when a venv is created
  • for the common venv, we'd need to track (in a file) which benchmarks have been done already
• only install requirements if not done already for the venv
  • track with a file (e.g. <venvroot>/.installed)
  • use a file to track what has already been installed in the venv
  • use pip freeze (or similar) to identify what has been installed already (requires the ability to verify requirements)

All that said, I'm not sure this alone is worth the effort. It might be worth it if combined with #157.

Inizia tracciando dove vengono installati i requisiti dei benchmark e come vengono creati gli ambienti virtuali comuni e specifici per ciascun benchmark. Confronta il tracciamento dei requisiti installati con il controllo dell’ambiente, inclusa l’interazione con l’issue #157. Il lavoro è completato quando le esecuzioni ripetute dei benchmark saltano il lavoro se le dipendenze sono già disponibili, senza compromettere la correttezza delle dipendenze.