End to end retrieval QA example

[dakinggg]

TODO:

• [x] top level readme
• [x] step 1 docs
• [x] step 2 docs
• [x] step 3 docs
• [x] step 4 docs
• [x] step 5 docs
• [x] step 6 docs
• [x] step 7 docs
• [x] what next docs
• [x] lint (and add to CI)
• [x] step 1 full run (oci://mosaicml-internal-checkpoints/sec_10k_demo/data/sec-10ks-{small|large})
• [x] step 2 full run (oci://mosaicml-internal-checkpoints/sec_10k_demo/data/sec-10ks-{small|large}-mds)
• [x] step 3 full run (oci://mosaicml-internal-checkpoints/sec_10k_demo/checkpoints/mpt-7b-10ks-finetune-{small-YY9G1w|large-caah7o}/latest-rank0.pt.symlink))
• [x] step 4 full run (oci://mosaicml-internal-checkpoints/sec_10k_demo/checkpoints/mpt-7b-dolly-{small-nNaKNn|large-Yfcb0k}/latest-rank0.pt.symlink)
• [x] step 5 full run (oci://mosaicml-internal-checkpoints/sec_10k_demo/checkpoints/mpt-7b-hf-{small|large})
• [x] step 6 full run (mpt-7b-finetuned-1b7xlc)
• [x] step 7 full run (instructor-large-u2hs4e)
• [x] try a big model
• [x] application testing
• [x] top level end to end examples readme
• [ ] some basic tests where applicable (won't do, deferring to regression runner implementation, and/or a follow up PR)
• [x] change examples to main (TODOs in code)
• [x] pin foundry (TODOs in code)
• [x] decide between PURE and FULL and fp16/bf16
• [ ] check the deployment yamls so they are up to date