ability to lock state.yml

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

I find the `status > recent repositories` panel very useful, esp. to keep track of commonly used repos.

One downside, however, is that you can't use lazygit in repos you *don't* want in `status > recent repositories`.

**Describe the solution you'd like**

Would be nice to be able to lock `recentrepos` in `state.yml` to prevent this.

**Describe alternatives you've considered**

Manually scrubbing unwanted repos from `state.yml`