Add usage_request and usage_reply based on psutil

[echarles]

This PR aims to start a discussion to add a new message type usage_request/usage_reply as discussed in the last JupyterLab meeting jupyterlab/frontends-team-compass#128 (comment)

On JupyterLab jupyterlab/jupyterlab#11285 is needed.

cc/ @Carreau

[echarles]

A JupyterLab extension example/experiment using this features is available on https://github.com/datalayer-experiments/jupyter-usage

[echarles]

@Carreau This is ready for review

[Carreau]

Rebased on master to see if it fixes the test failures. Those should have been fixed on main branch.

[echarles]

Super! Thx @Carreau

[jasongrout]

For clarification, for those reading this, usage_request and usage_reply are non-standard kernel messages right now (i.e., they are not in the kernel message spec, so they are specific implementation details of ipykernel).

[jasongrout]

The related JupyterLab PR, jupyterlab/jupyterlab#11285, is now closed:

I will close this one as we are not going to go further with this specific implementation. A potential more generic follow-up can be discussed in jupyterlab/jupyterlab#12117

If this message is not going to be used, should we revert this PR? @echarles?

[echarles]

The usage request/reply is consumed by https://github.com/Quansight/jupyterlab-kernel-usage