Resize `half` window size

[kleutzinger]

Is your feature request related to a problem? Please describe.

• I prefer the half view for my most common use cases. but for the file tree, the left hand side doesn't need to be that wide.
• I have this in my config

  
  gui:
  windowSize: "half"

**Describe the solution you'd like**
- It'd be nice to have a configurable value to set the width of the `half`. 
- there already exists   `sidePanelWidth: 0.3333 # number from 0 to 1`, but this is not respected by the `half` screen, only the `normal` screen.
- maybe something like `halfSidePanelWidth: ...` 

**Describe alternatives you've considered**
Staying in `normal` mode and resizing the left hand side via the `sidePanelWidth` option. But i prefer half

**Additional context**

- related issue: https://github.com/jesseduffield/lazygit/issues/2571

![image](https://github.com/jesseduffield/lazygit/assets/6435727/5166431e-5b64-466f-a820-c0bfa2a92cf7)
- I'd like to be able to resize the right pane to the size of the red box.

[mark2185]

Would you be interested in opening a PR? This seems like a good first issue.

It's okay if you're not interested :)

[kleutzinger]

i can give it a shot

[kleutzinger]

i couldn't figure out how to implement this myself.

[jesseduffield]

We should have four window sizes:

• normal
• tall
• half
• full

I still like having half for when you actually do want to see a little more of a window horizontally without taking up the full size.

[OliverJAsh]

This would also be useful for the commits panel. When I'm rebasing I want to see the full list of commits, but I want the diff to be as wide as possible.

[mark2185]

@OliverJAsh have you tried this?

gui:
  enlargedSideViewLocation: 'top'

That might be preferable to you, the commits list won't get in the way of the diff's width.

[OliverJAsh]

I tried that for awhile but I need more length on the commit list. When I'm rebasing I need to shuffle commits around so I want to see as much of the commits list as possible.