Adding MediaSum dataset

[AnnaWegmann]

Description

This adds the mediasum.rst file for documentation and the convert_mediasum-corpus.ipnyb for the script that was used to convert the mediasum dataset to a convokit corpus object. Find the zipped dataset here: https://drive.google.com/file/d/1cCaSuVUKN0B3s-GxnWg1gtWwOLNF66n0/view?usp=sharing to be added to your servers

Motivation and Context

add a dataset, see details in the .rst file, but this is based on
https://aclanthology.org/2021.naacl-main.474.pdf and https://aclanthology.org/2024.emnlp-main.52/

How has this been tested?

see convert_mediasum-corpus.ipnyb for the creation / testing outputs

Other information

corpus still needs to be added to your servers https://drive.google.com/file/d/1cCaSuVUKN0B3s-GxnWg1gtWwOLNF66n0/view?usp=sharing

[seanzhangkx8]

Hi Anna, thank you so much for your contribution to ConvoKit. It looks great. I will just add some configuration to support downloading the corpus from ConvoKit directly. After that I will merge the PR into our main branch. Thanks again for your work!