- Remove old attempt to sync scrolling
- Share a `ScrollAnchor` between the two sides, and be sure to resolve
it against the correct snapshot
- Allow either side to initiate an autoscroll request, and make sure
that request is processed in the same frame by the other side

Release Notes:

- N/A

---------

Co-authored-by: cameron <cameron.studdstreet@gmail.com>
Co-authored-by: Zed Zippy <234243425+zed-zippy[bot]@users.noreply.github.com>
Co-authored-by: Jakub <jakub@zed.dev>