Fix long lines wrap in split diff mode

Created by: oleggromov

Issue

This PR addresses https://github.com/sourcegraph/sourcegraph/issues/29888 Long lines of code weren't wrapped properly and caused text from the left column to overlap the right one.

Repro link: https://sourcegraph.com/github.com/angular/angular/-/commit/f593552cfe44ced74a3ec7e95a9ae847094fb632?visible=27

The fix

We could've applied some sort of horizontal scrolling, which isn't ideal in my opinion - because it would lead to harder to perceive UI, or force long lines to be split in a few. I chose the latter.

Before

After