feat: add inference and evaluation script with dataset transformations

[mattmazzola]

⚠️ This PR is not intended to merge directly, but to share work from our fork which may be useful to Metaseq ⚠️

Issue

1. Wanted a way to evaluate models using the same methods and commands we used for training them
2. Wanted a structured way to use different metrics or normalize differences depending on the dataset being tested
3. Wanted to use the same evaluation metrics used by Azure Babel for comparison
4. Wanted to be able to generate few-shot prompts for inference

Solutions

1. Add script for model inference and evaluation

   1. Add evaluation support for HuggingFace, ParlAI, COCO, Grindstone implementations of HELM metrics
   2. Update Docker file to install evaluation dependencies
      1. Unlikely to be correct modification
   3. Move _flatten_config to metaseq.utils as it used by multiple code

2. Add mappings between dataset and pipeline configuration of eval libraries, metrics, and transformation functions

   1. Metrics Example: Summarization datasets (Reddit and CNN-DM) should use evaluation libraries with ROUGE-L and BERTScore-F, but Classification datasets (HellaSwag and PIQA) should use evaluation libraries with Accuracy metric
   2. Transformation Example: HellaSwag model outputs (4) something something -> 4

3. Added necessary evaluation libraries and re-implemented some metrics

4. Add PromptGeneratror to create few-shot prompts based on configuration using Jinja templates

This PR is quite large so it may be hard to make sense of.
Originally was only going to be inference.py and few other modifications, but then I kept brining in missing dependencies to avoid gaps and it grew a lot 🤔

Testing

Did not test 😔

Related to: #726

Much of this work was done by @sahajgg, @tupini07, and @anselmwang 🙏

[tupini07]

If Metaseq has a standardized path for the vocab and merges files then we'll need to replace them here :) If not we might need to remove the default value.

[tupini07]

left some comments :)

[mattmazzola]

This likely isn't the correct place to make this change.

It is only snippet from our whole Dockerfile which adds the evaluation libraries

[mattmazzola]

This visualization may be important for understanding