[FEATURE REQUEST] Raw Text Support for GLI; New Dataset Arxiv-2023

[Jn-Huang]

Is your feature request related to a problem? Please describe.
Task 1: Add raw text loading support for GLI, which should cover cora, pubmed, cite seer, ogbn-product and ogbn-arxiv.
Task 2: Add new dataset arxiv-2023.

Describe the solution you'd like
As per discussion with Xingjian: Design Doc.

[Jn-Huang]

Task 2 is on this PR now.

[Jn-Huang]

Task 1 on this PR.