Refactor static functions.

Common static functions for manipulating metadata moved
from patial_metadata_interface to metadata_common.h

Common static functions for comparing equivalence with
metadata for tests moved to test_common.h

BUG: 30140438
TEST: Unit tests pass

Change-Id: I4310b4ff05bdd68f7f92f533028989914d0f4c82
diff --git a/modules/camera/3_4/metadata/control.h b/modules/camera/3_4/metadata/control.h
index db19b1d..4b4adcf 100644
--- a/modules/camera/3_4/metadata/control.h
+++ b/modules/camera/3_4/metadata/control.h
@@ -22,6 +22,7 @@
 #include <system/camera_metadata.h>
 
 #include "../common.h"
+#include "metadata_common.h"
 #include "tagged_partial_metadata.h"
 
 namespace v4l2_camera_hal {