Keep track of commands history across the sessions

**Is your feature request related to a problem? Please describe.**
For several times now I discarded something that shouldn't be discarded, and left the lazygit. Trying to be quick bites me in the ass. Discard is not tracked within a reflog, so undo doesn't work in this case.

**Describe the solution you'd like**
Recently you introduced command history, which is really great. It would save my ass if I would check it immediately. Unfortunately I left lazygit and the history was gone. I changed so many files that I lost a track of what I discarded. Having at least the file name that I discarded would help a lot.
My idea is just to keep the history in some cache file, for at least some amount of time. Something like bash does with `.bash_history` or zsh with `.zsh_history`. Of course, this would be an opt-in feature.

**Describe alternatives you've considered**
For now I'll add a `confirmOnQuit` to slow me down a little bit, but I don't know anything else that I could do. Maybe unbind `d` and have discard on something else where I need to think before doing it.

**Additional context**
I believe this shouldn't be too hard to implement, since data is there. It just needs to be appended to the cache file when lazygit is closed.