CORD-2312 unit tests for vsg syncsteps

Change-Id: I745bc90b0c27a28a430282611c79677569ec978d
(cherry picked from commit 3fa6a7ab207a3ef38a659ec37b5cc6f0d312416f)
diff --git a/xos/synchronizer/steps/test_private_key b/xos/synchronizer/steps/test_private_key
new file mode 100644
index 0000000..3cb08a3
--- /dev/null
+++ b/xos/synchronizer/steps/test_private_key
@@ -0,0 +1 @@
+some_key