Improve reusing old commit messages

**Is your feature request related to a problem? Please describe.**
In the commit summary window, I can press `` and `` (the arrow keys) to cycle between old commit messages. I use this feature a lot when making "save points" in my notes that I keep for work in a git repository, as well as my dotfiles config.

This works well, but sometimes I mix these repeated commits and new ones. Here is an example where I keep updating my neovim (text editor) plugin lock file:


**Describe the solution you'd like**
When I am in the commit summary window and press ``, let's somehow highlight the commit message whose message has been repeated.

Here, the matching commit message could be highlighted so what the next commit message is going to be I know when I press `` again to scroll further back the history:

**Describe alternatives you've considered**
Another way to do this could be to show the next + previous message summaries in the Commit summary window itself. This might be a better option if the Commits pane is not visible.