Confirm file download/write select/deselect UI

[kphurley]

If we do #5 , we'll already have the list to sync, so we should just pass this as a prop to SyncScreen when Sync! is pressed. It should then be able to select and deselect files to sync by clicking on the filename and then save the files to its native format (PGN to start with)

Once we finish this ticket, we will have MVP completed.