notebook and data from July 2024 webinar

[Dr-Irv]

There are 2 data files, and the notebook prompts you to pick one of the files.

For @simonbowly

[CLAassistant]

All committers have signed the CLA.

[simonbowly]

Thanks Irv, I'm working on integrating this with the rest of the examples in the docs.

[simonbowly]

@Dr-Irv I've moved these as-is into the existing webinars directory so we can point people to it: https://github.com/Gurobi/gurobipy-pandas/tree/main/webinar/2407-data-first

Opened #86 separately for integrating this into the docs (that might not happen until after the webinar).