Add conditional callbacks

Enable conditional application of callbacks.

Change-Id: I9d765e5f585aac40994b65da3b51ea891beae9bf
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/src/templates/conditional.mako.cpp b/src/templates/conditional.mako.cpp
new file mode 100644
index 0000000..3cc9564
--- /dev/null
+++ b/src/templates/conditional.mako.cpp
@@ -0,0 +1,3 @@
+std::make_unique<ConditionalCallback<ConfigPropertyCallbacks>>(
+${indent(1)}ConfigPropertyCallbackGroups::get()[${c.graph}],
+${indent(1)}*ConfigConditions::get()[${c.condition}])\