Accept configuration from argument or env

[Jomik]

It would be nice if we were able to configure lazyjj from somewhere other than the jj/config.toml
Specifically I'd like to be able to configure lazyjj with colors from neovim, when used in neovim.

Similar to what folke has done for lazygit in his snacks repo https://github.com/folke/snacks.nvim/blob/bc0630e43be5699bb94dadc302c0d21615421d93/lua/snacks/lazygit.lua#L43

[Cretezy]

Makes sense for me. I think we should have some option like LAZYJJ_JJ_CONFIG which passes down options to jj's --config, allowing to modify the color.