Support for new ipython / connection files format

[danielfleischer]

Current ipython has a different connection JSON format which looks like this:

  "base_url": "/",
  "hostname": "localhost",
  "password": false,
  "pid": 12345,
  "port": 8888,
  "root_dir": "/Users/dan",
  "secure": false,
  "sock": "",
  "token": "ABCDEFGH",
  "url": "http://localhost:8888/",
  "version": "1.13.1"

while this package expects something different; it lacks the fields shell_port, iopub_port, stdin_port, hb_port, transport which are defined in https://github.com/nnicandro/emacs-jupyter/blob/42a9765897ad36518b5371f558b36cdac3a0ec74/jupyter-base.el#L413-L427

Versions:

Package	Version
ipykernel	6.6.0
ipython	7.30.1
jupyter-client	7.1.0
jupyter-core	4.9.1
jupyter-server	1.13.1
jupyterlab	3.2.5
jupyterlab-server	2.9.0

[danielfleischer]

Related to #315.