Added PDF table extraction feature with aligned Markdown

[Ashhhh010101]

This PR introduces a new feature for the PdfConverter:

• Extracts tables from PDFs using pdfplumber.
• Converts tables into properly aligned Markdown format.
• Preserves all rows in the tables exactly as they appear.
• Normalizes whitespace in text blocks.
• Falls back to pdfminer if pdfplumber fails.

This improves Markdown output from PDFs, making tables clean, readable, and aligned without altering the original table content.

[lesyk]

This should solve the problem: #1499
If works, please close the request.

[Ashhhh010101]

Any updates or improvements on this PR @zashed @lesyk

[lesyk]

Well, I have merged my PR #1499 which solves this problem as I understand.

[Ashhhh010101]

Thanks for confirming, @lesyk.
Glad to see #1499 merged and resolving the issue.