Implement splitting vertically with syncing

[Lyndon-Mackay]

Implementing Sync VSplit Views (#7031)

Overview

The current implementation of the split view works as follows:

When a scroll event occurs, the editor's tree calls a function that synchronizes the views by scrolling the other panes to match the current view. This ensures that the left and right panes remain in sync, with the right view being a page down from the left view.
Limitations and Future Directions

Currently, I have limited the number of synced views to 2 per document, as unfocused views react to the focused views' scrolling actions. This is a simple implementation to get started with.

At this stage, the command cannot be used with different documents, but it could be changed in the future to support side-by-side scrolling of different files.

I have two questions regarding this implementation:

1. From a usability perspective, should I synchronize scrolling on searches?
2. How can I best initialize the new view to be a page down, as it will only start synchronizing on the first user scroll, which I find jarring?

I also noticed that I left some logging code inside, which I need to remove.

Any other feedback would be appreciated.
I especially would love to know a better way to write swap_sync_views implementation is entirely decided by what the borrow checker wants.

[Lyndon-Mackay]

Sorry about closure, thought I had to redo to convert to draft

[Lyndon-Mackay]

I had another look for question two.
I think in editor.rs I can call my new moved_sync function if I change the signature to use editor rather then context.
but I am not sure how to call commands::moved_sync
I will rename moved_sync as well open to suggetions

[the-mikedavis]

This adds a medium/large amount of code and complexity for something that's mostly cosmetic. I would prefer that something like this live as a plugin

[Lyndon-Mackay]

Ok I understand the plugin argument

I decided to make the extended split start a page down for my own sake.