Add convert_delta_to_json to CLI

[KuuCi]

This PR allows users to call llmfoundry convert_delta_to_json {ARGS} while maintaining correctness with existing convert_delta_to_json script. The motivation is for DLE where we want to make the CLI much more intuitive in the docker images

[KuuCi]

test-dt-orig-BK6Lv9 runs:

cd llm-foundry/scripts/data_prep
  python convert_delta_to_json.py \
      --delta_table_name "main.arxiv.data_chunked" \
      --json_output_folder data_folder \
      --cluster_id 0713-000001-a2kqt0bu
  ls
  ls data_folder

test-dt-cli-AT7lYi runs:

cd llm-foundry/scripts/data_prep
  llmfoundry convert_delta_to_json \
      --delta-table-name 'main.arxiv.data_chunked' \
      --json-output-folder data_folder \
      --cluster-id 0713-000001-a2kqt0bu
  ls
  ls data_folder

[KuuCi]

not entirely sure why smoketest is failing

[KuuCi]

mcli logs test-dt-orig-wEutZ2 runs:
python convert_finetuning_dataset.py \ --dataset "Muennighoff/P3" \ --splits train validation \ --preprocessor "llmfoundry.data.finetuning.tasks:p3_preprocessing_function" \ --out_root "data_folder"

mcli logs test-dt-cli-fVsqOh runs:
llmfoundry data_prep convert_finetuning_dataset
--dataset "Muennighoff/P3"
--splits train,validation
--preprocessor "llmfoundry.data.finetuning.tasks:p3_preprocessing_function"
--out-root "data_folder"

[KuuCi]

mcli logs test-dt-cli-52hYHv