support sample count in prompt_viewer

[cdpath]

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Motivation

Add support to print multi samples from dataset

Modification

Add a for loop to extract multiple prompts

Checklist

Before PR:

• Pre-commit or other linting tools are used to fix the potential lint issues.
• Bug fixes are fully covered by unit tests, the case that causes the bug should be added in the unit tests.
• The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
• The documentation has been modified accordingly, like docstring or example tutorials.

After PR:

• If the modification has potential influence on downstream or other related projects, this PR should be tested with those projects.
• CLA has been signed and all committers have signed the CLA in this PR.

[cdpath]

Also, I'd like to add a subcommand to dump prompts to unified dataset format (jsonl, for example).

[gaotongxiao]

Also, I'd like to add a subcommand to dump prompts to unified dataset format (jsonl, for example).

Sounds cool!