Allow multi-select in storage picker

app/src/main/java/org/tasks/dialogs/AddAttachmentDialog.kt

@@ -13,7 +13,6 @@ import org.tasks.activities.CameraActivity
 import org.tasks.extensions.Fragment.safeStartActivityForResult
 import org.tasks.files.FileHelper.newFilePickerIntent
 import org.tasks.preferences.Device
-import java.util.*
 import javax.inject.Inject
 
 @AndroidEntryPoint
@@ -68,7 +67,11 @@ class AddAttachmentDialog : DialogFragment() {
 
     private fun pickFromStorage() {
         targetFragment?.safeStartActivityForResult(
-                newFilePickerIntent(activity, null),
+                newFilePickerIntent(
+                    activity = activity,
+                    initial = null,
+                    allowMultiple = true,
+                ),
                 REQUEST_STORAGE
         )
     }

app/src/main/java/org/tasks/files/FileHelper.kt

@@ -26,11 +26,17 @@ import java.io.IOException
 import java.util.*
 
 object FileHelper {
-    fun newFilePickerIntent(activity: Activity?, initial: Uri?, vararg mimeTypes: String?): Intent =
+    fun newFilePickerIntent(
+        activity: Activity?,
+        initial: Uri?,
+        allowMultiple: Boolean = false,
+        vararg mimeTypes: String?,
+    ): Intent =
             Intent(Intent.ACTION_OPEN_DOCUMENT).apply {
                 putExtra("android.content.extra.SHOW_ADVANCED", true)
                 putExtra("android.content.extra.FANCY", true)
                 putExtra("android.content.extra.SHOW_FILESIZE", true)
+                putExtra(Intent.EXTRA_ALLOW_MULTIPLE, allowMultiple)
                 addCategory(Intent.CATEGORY_OPENABLE)
                 setInitialUri(activity, this, initial)