Start publishing both x86_64 and aarch64 VirtualBox VMs with Ubuntu 24.04 ubuntu-desktop-minimal with pre-built P4 dev tools

[jafingerhut]

I like the default Ubuntu desktop better than the one used by p4lang/tutorials, and many people are more familiar with it. Measure how much larger it is, but if it is about 1 GB or less extra space, that seems worth it to me.

Update: The above was completed in 2024-Dec in the p4lang/tutorials repo.

Also create steps for creating an aarch64 pre-built VM that runs on Apple Silicon Macs with Virtualbox 7.1.x, even if we don't use vagrant to create the images, but a combination of manual steps and some bash scripts. Document the sequence in a README somewhere. Even with the current tutorials vagrant scripts, there are manual steps I do every month -- just try to keep the manual steps short.

Update: As of 2025-Jan, VirtualBox 7.1.4 is the latest version, and on Apple Silicon Macs the File->Export Appliance feature does not seem to work. I guess I will have to wait for a later version when that feature has been made operational.