add own directory

[wibi9424]

like another app example ppsspp, he asking us to choose where the directory for the app, so when we grant it, ppsspp can only read that directory, he will create many folder inside it like game folder, save data folder etc, if this can be applied for this app, i think we no need to granted this app to read everything in the phone, also we have 1 directory that has saved files, singer files, and other files that might openutau mobile need it when we open the app, then if we want to open project, the saved file can be placed in the root, no need to open many folder, or open saved file from saved folder, then open audio file in audio folder, it would be quick open, and easier to find files

i also hope that you can remove "allow acces all files" for reading files