Filter out or collapse merge commits in the Commits panel

### Is your feature request related to a problem? Please describe.
In big monorepos merge commits make the Commits log unusable

### Describe the solution you'd like
Commit Log Options to hide/collapse merge commits

### Describe alternatives you've considered
Not using the Commit panel and switching to `git log --oneline trunk..HEAD` or `git log --first-parent --no-merges`

### Additional context
There is a proof of concept https://github.com/levabala/lazygit/tree/feature/collapse-merge-commits

Related issues:
#3575