This blocks until the editor is closed.
text - The text to edit.
editor - The path to the editor to use. Defaults to automatic detection.
env - Environment variables to forward to the editor.
requireSave - If the editor is closed without saving, null will be returned if true, otherwise
text will be returned.
extension - The extension of the temporary file that the editor will open. This can affect syntax
CliktError - if the editor cannot be opened.
Return The edited text, or null if requireSave is true and the editor was closed without saving.