Add S3 based optimization cache support

We use kiwix_storagelib for implementing S3 based optimization cache in the scrapers. However, this gives rise to redundant code. We put a version of the file along with the optimizer version as the metadata always. So, this can be better implemented in scraperlib. For a start, we can have a caching module that can have 3 functions, (or maybe a class containing methods). The primary 3 things we need are -

• download_from_cache()
• upload_to_cache()
• check_credentials()

There can be several ways to have this, but it should at least fulfill the following -

• Compare optimizer_version
• Compare file_version

Optional things can be to check file upload date and discard if it's older than a specified amount of time. If we go for a class based approach, we can also explore possibilities to improve performance.

Inizia esaminando l’uso esistente di kiwix_storagelib negli scraper e il modo in cui le versioni di optimizer e dei file vengono memorizzate come metadati. Definisci il punto di ingresso della cache e verifica che credenziali, download, upload ed entrambi i confronti delle versioni siano coperti; nell’issue non vengono indicati file o test specifici.