Add data_columns support in TableIndex

Author: vgvoleg

ydb/table.py

@@ -290,6 +290,7 @@ def __init__(self, name):
         self._pb.name = name
         self.name = name
         self.index_columns = []
+        self.data_columns = []
         # output only.
         self.status = None
 
@@ -307,6 +308,12 @@ def with_index_columns(self, *columns):
             self.index_columns.append(column)
         return self
 
+    def with_data_columns(self, *columns):
+        for column in columns:
+            self._pb.data_columns.append(column)
+            self.data_columns.append(column)
+        return self
+
     def to_pb(self):
         return self._pb