Re-release consolidated OPT / OPT-IML checkpoints

Created by: suchenzang

After https://github.com/facebookresearch/metaseq/pull/459 and https://github.com/facebookresearch/metaseq/pull/556, we can now release updated checkpoints that are consolidated from FSDP shards with different model parallelism as well. We should update all of our checkpoints as a start to help address some of the following painpoints that users are facing:

• https://github.com/facebookresearch/metaseq/issues/595
• https://github.com/facebookresearch/metaseq/issues/594
• https://github.com/facebookresearch/metaseq/issues/574
• https://github.com/facebookresearch/metaseq/issues/567
• https://github.com/facebookresearch/metaseq/issues/475
• https://github.com/facebookresearch/metaseq/issues/407
• https://github.com/facebookresearch/metaseq/issues/233
• https://github.com/facebookresearch/metaseq/issues/211

and previous issues:

• https://github.com/facebookresearch/metaseq/issues/31
• https://github.com/facebookresearch/metaseq/issues/125

We have internal consolidated versions for 2.7B and 30B to check against, and will also need to confirm that generation looks roughly sane after consolidation.