Allow Binding Internal Functions to Custom Keybindings in Vim Mode

[Aneeqasif]

Marimo notebooks already provide Vim mode with .vimrc support, which is great for modal editing workflows.
It would be highly useful to allow users to bind custom/internal functions to keybindings that can trigger notebook or cell-level actions like

• Toggling cell folds
• Running or stopping cells,
• Triggering user-defined UI actions
• Lsp actions

This can make Marimo more extensible and customizable, similar to advanced editors like VS Code, JetBrains IDEs, or Emacs