Add ImageNet21K ViT-L/32 config.
Add ImageNet21K ViT-L/32 config.

To make this config, I

+ Start from jft300m_vit_l32.py.
+ Cross-reference changes with dune codebase's i21k_large.py.
+ Verify jft300m_vit_l32.py has no differences with dune codebase's jft300m_vit_large32.py.

PiperOrigin-RevId: 422490349

google/uncertainty-baselines