Replace data URL in SAMSum dataset and support streaming
_The documentation is not available anymore as the PR was closed or merged._
This PR replaces data URL in SAMSum dataset:
- original host (arxiv.org) does not allow HTTP Range requests
- we have hosted the data on the Hub (license: CC BY-NC-ND 4.0)

Moreover, it implements support for streaming.

Fix #4146.
Related to: #4236.

CC: @severo 