Metadata update support RomM -> Device #265

Is your feature request related to a problem? Please describe.
Sometimes Grout fails a complete download and then forgets to update a game description or some other kind of metadata, or maybe the RomM server has updated metadata that I'd like to sync to the device for a game.

Describe the solution you'd like
Just like there's a tool to (re)download art, it would be nice to have a similar option to update the gamelist from within Grout as to keep the metadata in line with the RomM server

Describe alternatives you've considered
I've looked at letting RomM generate a gamelist, but this takes far too much effort to convert and move to my device, and scraping might not result in the same metadata being inserted

Additional context
It would be extra nice if there can be filters on what fields Grout will overwrite for a game, i'd like to be able to keep my launches, playtime and favourite status for example while updating/overriding a game description