Visualizing hidden lifetime captures

[willcrichton]

A particularly confusing kind of Rust error occurs when traits obscure lifetimes, such as the closure here: https://rust-book.cs.brown.edu/ch13-01-closures.html#closures-must-name-captured-lifetimes

We would like Aquascope to be able to visualize these kinds of implicit lifetime captures when they occur. On a technical level, that requires working with the member constraints inferred by the borrow checker.