Incorporate Android's MediaStore into Qt for Android

Android 11 and above enforces the new scoped storage which won't allow Qt to properly manage (read/write) files on Android. The scoped storage was introduced before api 29 but it's being enforced on api 30 so apps need to migrate to the new approach. Android offers a way to opt out of this by using the manifest flag, but this will be ignore starting from api 30.

android:requestLegacyExternalStorage="true"

Qt should look for ways to incorporate these changes and make it easier again to handle files i/o. Also, it's worth mentioning that the Storage Access Framework works with Qt and it allows opening/saving files but requires user interaction, but with the MediaStore api it's possible to manage files without user interaction.

References: 

• https://developer.android.com/training/data-storage/use-cases
• https://developer.android.com/training/data-storage
• https://developer.android.com/training/data-storage/shared/media