Rename fillMap and move it for reuse

The tree is still being filled, but it's no longer a map, so let's
change the name. Also, I want to use this function in the upcoming
in-memory data tree.

Change-Id: I472c0b323d6097fbf23305085df8f905aa22cac5
diff --git a/src/libyang_utils.hpp b/src/libyang_utils.hpp
index 42b6198..d8bf4ad 100644
--- a/src/libyang_utils.hpp
+++ b/src/libyang_utils.hpp
@@ -7,5 +7,7 @@
 
 #include <libyang/Tree_Data.hpp>
 #include "ast_values.hpp"
+#include "datastore_access.hpp"
 
 leaf_data_ leafValueFromValue(const libyang::S_Value& value, LY_DATA_TYPE type);
+void lyNodesToTree(DatastoreAccess::Tree& res, const std::vector<std::shared_ptr<libyang::Data_Node>> items, std::optional<std::string> ignoredXPathPrefix = std::nullopt);