Add Schema::leaftypeName

Will be sued in the upcoming describe command.

Change-Id: I9ddecf8d3da1f82e8ce671210d51f31f895a9d27
diff --git a/src/yang_schema.hpp b/src/yang_schema.hpp
index 1165094..c763ea6 100644
--- a/src/yang_schema.hpp
+++ b/src/yang_schema.hpp
@@ -40,6 +40,7 @@
     const std::set<std::string> listKeys(const schemaPath_& location, const ModuleNodePair& node) const override;
     yang::LeafDataTypes leafType(const schemaPath_& location, const ModuleNodePair& node) const override;
     yang::LeafDataTypes leafType(const std::string& path) const override;
+    std::optional<std::string> leafTypeName(const std::string& path) const override;
     yang::LeafDataTypes leafrefBaseType(const schemaPath_& location, const ModuleNodePair& node) const override;
     yang::LeafDataTypes leafrefBaseType(const std::string& path) const override;
     std::string leafrefPath(const std::string& leafrefPath) const override;