save Data
Saves the data of all guilds to the database. This method saves the data of all guilds to the database, including their vault cache. The method iterates through the `guilds` list and calls the `saveVaultCache` method for each guild to save their vault cache. After that, the `saveGuilds` method of the database's `GuildAdapter` is called to save all guilds to the database.
Throws
if an I/O error occurs during the save process.