Android: Implement DocumentProvider

This allows users to access the Dolphin user directory.

Source/Android/app/src/main/AndroidManifest.xml

@@ -155,6 +155,18 @@
                 android:resource="@xml/nnf_provider_paths"/>
         </provider>
 
+        <provider
+            android:name=".features.DocumentProvider"
+            android:authorities="org.dolphinemu.dolphinemu.user"
+            android:grantUriPermissions="true"
+            android:exported="true"
+            android:permission="android.permission.MANAGE_DOCUMENTS"
+            android:enabled="@bool/enableDocumentProvider">
+            <intent-filter>
+                <action android:name="android.content.action.DOCUMENTS_PROVIDER" />
+            </intent-filter>
+        </provider>
+
     </application>
 
 </manifest>