Assign Platform Game folder when importing

Provide the ability to set the default game folder location for ROMs when importing. I often have my ROM library located in another location isolated from LaunchBox Library.

When adding ROMs to a new platform, I specify LaunchBox to locate ROMs in a remote directory, but there is no way to quickly tell LaunchBox to use it as my default Game folder for the platform, and have to manually reassign it for each platform under "Manage Plarforms..." dialog.