add GLEM model, TAGDataset and example of GLEM

[ECMGit]

reopened #9591

Feature summary:

• Add GLEM as GNN & LLM Co-training model to PyG
• adapt GLEM's LM to AutoModelForSequenceClassification from transformers
• Lora support
• LM/LLM support
• ogbn-products/ogbn-arxiv testing finished
• TAGDataset can be used as a wrapper class for any node classification dataset in PyG with LM tokenizer and associate raw text
• external prediction as pseudo labels supported

[codecov]

Codecov Report

Attention: Patch coverage is 11.93182% with 155 lines in your changes missing coverage. Please review.

Project coverage is 86.91%. Comparing base (f5c8293) to head (7c648f9).

Files with missing lines	Patch %	Lines
torch_geometric/nn/models/glem.py	11.42%	155 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9662      +/-   ##
==========================================
- Coverage   88.13%   86.91%   -1.23%     
==========================================
  Files         482      483       +1     
  Lines       31421    31592     +171     
==========================================
- Hits        27693    27458     -235     
- Misses       3728     4134     +406     

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[puririshi98]

LGTM just get CI green

[puririshi98]

@rusty1s @akihironitta ready for your reviews

[akihironitta]

Could we have type annotations all over the PR? Also, I'd suggest splitting this PR into smaller ones.

[akihironitta]

I haven't had a look outside the example script yet, but this addition is exciting! 🚀

[puririshi98]

LGTM @akihironitta @rusty1s let us know if anything else needed