vty_test: add artificial node levels for better testing

In vty_test, add three levels of parent nodes (level1, level2, level3) with
each having a leaf child (child1, child2, child3).

Use these to enhance the vty_test cfg files and test more diverse situations.

The current VTY code expects a go_parent_cb() to be present, otherwise it will
bump right back to the CONFIG_NODE, which will not work with more than one node
level below the CONFIG_NODE. Hence provide a minimal go_parent_cb().

Change-Id: Ib9bcf58b655fbd85e196f363fb7d8305d7dfc997
diff --git a/tests/vty/ok_more_spaces.cfg b/tests/vty/ok_more_spaces.cfg
index b66a9c2..263c682 100644
--- a/tests/vty/ok_more_spaces.cfg
+++ b/tests/vty/ok_more_spaces.cfg
@@ -1,4 +1,28 @@
-line vty
-  no login
-  no login
-log stderr
+level1 a
+    child1 a
+    level2 a
+        child2 a
+        level3 a
+            child3 a
+level1 b
+    child1 b
+    level2 b
+        child2 b
+level1 c
+    child1 c
+    level2 c
+        child2 c
+        level3 c
+            child3 c
+    level2 d
+        child2 d
+level1 e
+    child1 e
+    level2 e
+        child2 e
+    level2 f
+        child2 f
+level1 g
+    child1 g
+level1 h
+    child1 h