WRITE_EXTERNAL_STORAGE no longer provides write access, fix that

[Trilarion]

from lint: Scoped storage is enforced on Android 10+ (or Android 11+ if using requestLegacyExternalStorage). In particular, WRITE_EXTERNAL_STORAGE will no longer provide write access to all files; it will provide the equivalent of READ_EXTERNAL_STORAGE instead.

The MANAGE_EXTERNAL_STORAGE permission can be used to manage all files, but it is rarely necessary and most apps on Google Play are not allowed to use it. Most apps should instead migrate to use scoped storage. To modify or delete files, apps should request write access from the user as described at https://goo.gle/android-mediastore-createwriterequest.

To learn more, read these resources: Play policy: https://goo.gle/policy-storage-help Allowable use cases: https://goo.gle/policy-storage-usecases
More info: https://goo.gle/android-storage-usecases