fix:Fix a bug that returns null when the passed path is a file.

[jiangbo721]

Now it is changed to two parameters, if it is a folder, it will recursively get the files under the folder, if it is a single file address, it will only get the file. At the same time, the order of parameters is adjusted to be consistent with the display order, and the text is also optimised (to avoid users not knowing how to input parameters).

Summary

Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. List any dependencies that are required for this change.

Tip

Close issue syntax: Fixes #<issue number> or Resolves #<issue number>, see documentation for more details.

Screenshots

Before	After
...	...

Checklist

Important

Please review the checklist below before submitting your pull request.

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

[jiangbo721]

old:

new: