DM-12797 Firefly version of DM stack tutorial

[stargaser]

This pull request responds to the review at lsst-dm-tutorial#4

The repository has been moved to this new location.

• The tutorial-firefly notebook now contains only afw_display commands using the lsst.display.firefly backend.
• matplotlib displays have been removed
• firefly_client API usage has been removed
• the server at https://jupyterlabdemo.lsst.codes is now used, now that fixes have been made to make firefly_client and display_firefly work with https.

[SimonKrughoff]

This looks good to me. I'm really happy how things are working in the jupyterlab environment.