feat: configurable keybindings

[zachvalenta]

What changed

• added configurable keybindings!

Why

• I was trying out deff and my fingers found their way to my lazygit keybinds and I thought, "hey, deff should have configurable keybindings, too!"

User-facing impact

• none, unless you want to plop a config file at $XDG_CONFIG_HOME/deff/config.toml and tweak your setup

Validation

• cargo check --locked
• Manual testing completed (if applicable)

Checklist

• PR is focused and scoped to one change
• Docs updated when behavior changes
• Breaking changes called out (if any)

[flamestro]

Thanks for the suggestion! I have been busy the recent days and will look into this asap.

[flamestro]

Hi @zachvalenta, this looks good to me!
one issue I found it that the legend is not updated accordingly. I will fix this in a follow up PR