BigQuery: Client.list_rows should prefetch the first page and populate total_rows and other attributes #4152
Description
Return value doc:
:returns: Iterator of row data :class:`tuple`s. During each page, the
iterator will have the ``total_rows`` attribute set,
which counts the total number of rows **in the table**
(this is distinct from the total number of rows in the
current page: ``iterator.page.num_items``).
The iterator does not have the total_rows attribute or a page attribute either.
Can fetch_data() get a count of all rows or the only way is to iterate and count?