Bloom custom ckpt files, improved model path support, MII refactor, flake8, etc.

[jeffra]

• Task specific request_dict parsing, ensures required keys are given for each task type.
• Support appending model_path and aml model path in aml deployments
• Pass checkpoint dict to ds-inference instead of writing to file
• Add flake8 pre-commit and associated fixes
• Big refactor of overall code structure

Requires DeepSpeed version that includes this: deepspeedai/DeepSpeed#2132

[mrwyattii]

Looks good so far