Save files management fix

[JamesATeasdale]

I have been trying to migrate my save from the drastic emulator over to lemuroid since it's clearly superior, but I'm having issues with save files. It seems like this is more to do with newer versions of android than it is to do with lemuroid itself, but it's something that the developers can hopefully fix.

Basically, on newer android systems, lemuroids saves can be accessed with material files, but they can't be replaced, only copied. Other apps can allow both reading and writing as provided in the attached screenshot (I have a lot of experience editing the files of pojav launcher and retro arch, it's easy because they appear on the list). It would be very useful if lemuroid could have similar permissions to these other apps as it's the only thing holding it back when it comes to migration.

Also, the Google drive cloud sync files are hidden. I'm not sure if this is by Google drive's design, but it would be great if that was fixed too.

Thanks.