Feature request: C-x C-e to open the current prompt inside the editor [TUI parity with Unix tools and Aider TUI]

Exactly like Bash does it -- from its man page: `` edit-and-execute-command (C-x C-e) Invoke an editor on the current command line, and execute the result as shell commands. Bash attempts to invoke $VISUAL, $EDITOR, and emacs as the editor, in that order. ` Of course one could always get to the beginning of the line, type in /editor`, and press enter, but I figured it could be a nice addition. If there is appetite for including this, I might even try to implement this myself.

Like in https://github.com/Aider-AI/aider/issues/3630