Extend support for streaming datasets that use os.walk
Nice. I'll update the dataset viewer once merged, and test on these four datasets
This PR extends the support in streaming mode for datasets that use `os.walk`, by patching that function.

This PR adds support for streaming mode to datasets:
1. autshumato
1. code_x_glue_cd_code_to_text
1. code_x_glue_tc_nl_code_search_adv
1. nchlt

CC: @severo 