Proposal: Add SetRowsWithAnchor to Table for stable reverse pagination

[iMithrellas]

I'm working on a TUI using bubbles/table that involves reverse pagination (loading older items like chat history), and I've run into an issue where prepending rows causes the viewport to jump.

Currently, SetRows doesn't account for the internal virtualization window shifting when the row count changes at the top. Manually patching YOffset is brittle because m.start (internal state) also shifts.

Proposed Solution:
I've implemented a SetRowsWithAnchor(rows []Row, prepended int) method locally. It calculates the shift in the virtualization window and adjusts YOffset so the user's view remains stable.

I have the implementation and tests ready. Would you be open to a PR for this?
You can see the implementation in my fork: https://github.com/iMithrellas/bubbles