Support diff-so-fancy patch mode by using `--patch` when building code sets

I have Lazygit configured to use diff-so-fancy per your [excellent documentation](https://github.com/jesseduffield/lazygit/blob/master/docs/Custom_Pagers.md#diff-so-fancy). I would love to see Lazygit support d-s-f while in patch mode also. If a user wants to include parts of a file in their commit they can run `git add . --patch` and d-s-f will highlight the patch pieces appropriately.

Is it possible for Lazygit to use `--patch` for it's internal patch mode text selection?

-- Scottchiefbaker / Diff-so-Fancy lead developer