[Documentation]: Gambit tutorials - case studies from various domains

[edwardchalstrey1]

Requested documentation improvement

Replicate parts of papers which use Gambit as PyGambit tutorials available on the documentation site and as interactive Jupyter notebooks.

Follows from #542

Possible examples

• Economics example:
• Cybersecurity example: Empirical Mixnet Design
• Multi agent systems example:

[edwardchalstrey1]

Related to #240