el/dot-emacs.el: Apply `extend' setting to all(?) the applicable fonts.

[profile] / dot / jupyter-notebook.json

{
  "Cell": {
    "cm_config": {
      "lineNumbers": false
    }
  },
  "CodeCell": {
    "cm_config": {
      "autoCloseBrackets": false,
      "indentUnit": 2,
      "tabSize": 2
    }
  }
}