Pass database path to every database_open invocation

This fixes umr complaining about missing databases when there is no database in system directories, but a valid database path is given over commandline/envvar options.

I often use umr on my Steam Deck, and since the Deck has a read-only root filesystem, installing the database to system directories would be cumbersome. It's much easier to have a copy of the database in the home directory and pass a path to it via commandline options.