Support Placeholder Replacement for Extracted Tables

### Question
I am currently using Docling to extract figures and tables from an input PDF file. I'm glad to see that this task can be accomplished quite straightforwardly with your library by following the relevant section on this documentation page: https://docling-project.github.io/docling/examples/.

A highly desirable feature would be the ability to contextually extract these items (figures and tables), store them separately, and then replace them in the original input file with something else — such as a placeholder or an embedded version of the extracted item.

From what I understand, this seems achievable for images by using the `image_mode `and `image_placeholder `parameters in the `save_to_markdown `method. However, I haven't found a similar mechanism for handling tables.

Is there a way to accomplish this for tables natively with Docling?
If not, do you think this would be a valuable feature to propose?

Start with the relevant extraction example on the Docling documentation examples page and inspect the save_to_markdown method, including its image_mode and image_placeholder parameters. Define and document the expected behavior for extracted tables, including how table placeholders or embedded versions should appear, before identifying the implementation and tests that would need to change.

Written by the indexing model from the issue text.