Add MANAGE_EXTERNAL_STORAGE permission

[iovita083]

Describe the bug:
When setting up the app or adding a console, adding a ROMs directory does nothing unless you give the app files permission (adb shell appops set com.iisulauncher MANAGE_EXTERNAL_STORAGE allow)

Steps to reproduce the behavior:

1. Install iiSU
2. Select ROMs folder (on internal storage)
3. Nothing happens

Expected behavior:
ROMs folder is recognized as expected

Information:

• Device: Retroid Pocket 4 (non pro)
• OS: Android 11
• Browser: Don't have any installed other than the system webview
• Version: (iiSU: 0.0.5) (RP4: OTA 1.0.0.91)