rbd: add support for flattenMode option for replication

This commit adds support for flattenMode option
for replication.
If the flattenMode is set to "force" in
volumereplicationclass parameters, cephcsi will
add a task to flatten the image if it has parent.
This enable cephcsi to then mirror such images after
flattening them.
The error message when the image's parent is
in trash or unmirrored is improved as well.

Signed-off-by: Rakshith R <rar@redhat.com>

internal/rbd/rbd_util.go

@@ -703,6 +703,22 @@ func (ri *rbdImage) trashRemoveImage(ctx context.Context) error {
 	return nil
 }
 
+// DeleteTempImage deletes the temporary image created for volume datasource.
+func (rv *rbdVolume) DeleteTempImage(ctx context.Context) error {
+	tempClone := rv.generateTempClone()
+	err := tempClone.deleteImage(ctx)
+	if err != nil {
+		if errors.Is(err, ErrImageNotFound) {
+			return tempClone.ensureImageCleanup(ctx)
+		} else {
+			// return error if it is not ErrImageNotFound
+			return err
+		}
+	}
+
+	return nil
+}
+
 func (ri *rbdImage) getCloneDepth(ctx context.Context) (uint, error) {
 	var depth uint
 	vol := rbdVolume{}