Migrate Leios prototype setup into this repository

[dnadales]

The Leios prototype setup as of end of November currently resides in a branch in ouroboros-consensus, which supersedes the October branch. We should migrate this to the ouroboros-leios repository, and include:

• A README with instructions on how to run the demo with a single command (using nix).
• An explanation of the different demo artifacts, including what the user should expect to see and the Grafana charts that are set up.
• A prototype logbook, which contains the findings of the previous two demos (see the READMEs of the branches above).