Control Mode Support

[xavier83]

Implement a Control Mode similar to tmux's Control Mode, enabling external programs to interact with Zellij via a structured text-based protocol.

Why?
Control Mode allows external tools, such as terminal emulators and automation scripts, to manage sessions, windows, and panes efficiently. It enables integration with terminal UIs and remote SSH workflows without direct user interaction.

Expected Behavior
A command-line flag (e.g., zellij -C) to start a client in Control Mode.
Commands issued in Control Mode return structured responses.
Asynchronous notifications for session, window, and pane events.
Ability to send pane output as structured text instead of raw terminal rendering.
References
tmux Control Mode Documentation
Existing Terminal Emulator Support
Would love to hear the maintainers' thoughts on whether this aligns with Zellij’s goals! 🚀

[imsnif]

You might be interested in this discussion: wezterm/wezterm#4889