New file:
* `dao_product_last_access.dart`: Table that stores the local last access timestamp for a product.

Impacted files:
* `local_database.dart`: new version of the database, because of the new "product last access" table
* `new_product_page.dart`: added a call to refresh the product "last access" timestamp
* `offline_data_page.dart`: added a call to delete the product "last access" timestamps
* `product_model.dart`: added a call to refresh the product "last access" timestamp
* `pubspec.lock`: wtf