Re-run diff pager on terminal size change

**Describe the bug**

When the terminal is resized, the git diff isn't reproduced. This can mean line breaks don't get updated, eg. when using delta.

**To Reproduce**

1. Set delta (with colour) as your pager.
2. Open Lazygit to view a diff.
3. Resize the window.

**Expected behavior**

The pager should be re-run, ideally with an effort made to keep its view scrolled to the same place in the new terminal size.

**Screenshots**

Before resize:

After:

**Version info:**

```
commit=, build date=, build source=voidlinux, version=0.48.0, os=linux, arch=amd64, git version=2.49.0
```

**Additional context**

n/a