feat(kontemplate): defaults can now have nested values

See https://b.tvl.fyi/issues/409 for details.

Change-Id: Ibb54fab7a78e0e5f708c2a7dc8bb26ac0b2b4689
Signed-off-by: Armin Schlegel <a.schlegel@gridx.de>
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11972
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>

ops/kontemplate/util/util_test.go

@@ -47,6 +47,9 @@ func TestMergeWithNilMap(t *testing.T) {
 func TestMergeMaps(t *testing.T) {
 	map1 := map[string]interface{}{
 		"foo": "bar",
+		"baz": map[string]interface{}{
+			"qux": "quux",
+		},
 	}
 
 	map2 := map[string]interface{}{
@@ -56,6 +59,9 @@ func TestMergeMaps(t *testing.T) {
 	result := Merge(&map1, &map2)
 	expected := map[string]interface{}{
 		"foo": "bar",
+		"baz": map[string]interface{}{
+			"qux": "quux",
+		},
 		"bar": "baz",
 	}