Add a day 5 class on unsafe Rust

[randomPoison]

Currently we briefly introduce unsafe Rust at the end of day 4, but there's a lot more to go into with unsafe Rust. I think we could have an entire day 5 course going into more detail with unsafe Rust. There's enough to cover with unsafe that we couldn't fit it all in one day, so I think we should aim for the goal of getting students ready to review unsafe code, rather than trying to get students to the point where they could write unsafe themselves.

[fw-immunant]

It would be good to investigate ways to validate unsafe code here. Candidates include Miri, Kani, and VeriFast. I'm only familiar with Miri at present.

[andriyDev]

When you say "day 5 class" do you mean an additional optional day like the Concurrency class? Or do you mean extending the "main" course to be 5 days long?

[randomPoison]

I meant an optional extra day like Android or concurrency, I don't wanna add a day 5 to the main course lol