change the jupyter sage kernel to be MUCH simpler (in our Docker container)

[williamstein]

I just created this 2-liner kernel – incredibly simple and works fine; this is massively simpler than what is currently in our Docker image.

~/.local/share/jupyter/kernels/sageroed$ more kernel.json
{
 "display_name": "David Roe's SageMath",
 "argv": ["/projects/da1818ed-996d-4de6-acc6-361415b7725d/Src/sage-roed/sage", "--python", "-m", "sage.repl.ipython_kernel","--m
atplotlib=inline", "-f", "{connection_file}"]
}
~/.local/share/jupyter/kernels/sageroed$ ls
kernel.json
~/.local/share/jupyter/kernels/sageroed$

[williamstein]

Fixed now.

[slel]

Could this be an inspiration to solve the problem at #2351 about
adding a Jupyter kernel for a user-installed Sage?