Option for topological ordered log tab

**Is your feature request related to a problem? Please describe.**
I prefer topological ordering of commits (as seen in `git log --topo-order`) to chronological ordering in commit logs, as I find it easier to understand the history (without looking at a commit graph) due to the way it groups commits from one branch together

**Describe the solution you'd like**
This could either be implemented as a keybinding which toggles commit ordering between chronological and topological, or as an entry in a configuration file. (or both).
Though since gitui doesn't have a general config file (that I'm aware of? just the keybindings and theme ones?), the latter might not be the right solution

**Describe alternatives you've considered**
The git CLI itself has an option for logs to be ordered like this using the `--topo-order` flag, which can be formatted using the ``--pretty`` flag
E.g.
```
git log --topo-order --date=short --pretty="%Cred%h%Creset %<(20,trunc)%an %Cgreen(%ad)%Creset %s"
```
It works, and I have an alias for this, but it's a little awkward to use because I have to exit gitui to run it, and then enter back into gitui after. And obviously it'd be better if it was interactive as well

**Additional context**
I'd be interested in having a go at implementing this myself, though I'm not super familiar with Rust, so some pointers would be helpful

この issue ではファイルもテストも指定されていないため、まず gitui のコミットログのエントリポイントと、Git log コマンドを構築するコードを見つけます。既存のキーバインドとテーマの設定パスを確認し、選択した並び順を切り替えたり設定したりできること、そしてインタラクティブなログに反映されることを検証します。

索引モデルが issue の本文から書いたものです。