Handle CSV rows in WithParam

# Summary

The `WithParam` field currently supports only JSON and YAML. However, there're several needs in my team that they want to run a step for each rows in a CSV file.

# Motivation

We have CSV files which need to be parsed and run a step for each row.

# Proposal

Either of the following items are possible.

- `WithParam` automatically identify CSV format and parse it.
- Create another field like `WithCSV`.
- Add another field in `outputs` like `converter: csv` and pass converted json to `WithParam`

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**Message from the maintainers**:

If you wish to see this enhancement implemented please add a 👍 reaction to this issue! We often sort issues this way to know what to prioritize.

Start at the WithParam field and inspect how its existing JSON and YAML inputs are parsed and expanded into per-step items. Resolve which of the three proposed interfaces should be supported, then verify that CSV rows can drive one workflow step each and validate the chosen behavior.

Written by the indexing model from the issue text.