Draft: API: remove UniqueResult, lower-case at, size for ResultSet

Summary

• Remove UniqueResult
• At and Size are lower-case now (ResultSet, MultiResultSet)

src/ccaosdb.cpp

@@ -333,8 +333,9 @@ ERROR_RETURN_CODE(GENERIC_ERROR,
                     auto *wrapped_transaction =
                       static_cast<caosdb::transaction::Transaction *>(
                         transaction->wrapped_transaction);
-                    wrapped_transaction->Execute();
-                    return 0;
+                    wrapped_transaction->ExecuteAsynchronously();
+		    auto status = wrapped_transaction->WaitForIt();
+                    return status.GetCode();
                   })
 
 ERROR_RETURN_CODE(GENERIC_ERROR,