Reworked get_game_path() and browse_dir() in wine runner

Made get_game_path() just return the prefix path or global path and
moved the things specific to browse_dir() for wine in browse_dir().
Fix get_browse_dir() returning game.directory
Create working_dir base
working_dir for Linux runner
working_dir for Dosbox
Remove now useless self.game_path in Linux
Rename wineexec option "workdir" => "working_dir"
Shouldn't have removed this error check
Get rid of self.game_path altogether