Support both signatures for tag_invoke

Author: kinyoklion

libs/internal/include/launchdarkly/serialization/json_flag.hpp

@@ -77,6 +77,11 @@ void tag_invoke(
     boost::json::value& json_value,
     data_model::Flag::VariationOrRollout const& variation_or_rollout, const VariationOrRolloutContext&);
 
+void tag_invoke(
+    boost::json::value_from_tag const& unused,
+    boost::json::value& json_value,
+    data_model::Flag::VariationOrRollout const& variation_or_rollout);
+
 void tag_invoke(
     boost::json::value_from_tag const& unused,
     boost::json::value& json_value,

libs/internal/src/serialization/json_flag.cpp

@@ -273,6 +273,13 @@ void tag_invoke(
         variation_or_rollout);
 }
 
+void tag_invoke(
+    boost::json::value_from_tag const& unused,
+    boost::json::value& json_value,
+    data_model::Flag::VariationOrRollout const& variation_or_rollout) {
+    tag_invoke(unused, json_value, variation_or_rollout, VariationOrRolloutContext());
+}
+
 void tag_invoke(boost::json::value_from_tag const& unused,
                 boost::json::value& json_value,
                 data_model::Flag::Prerequisite const& prerequisite) {