improve `BitAnd` trait documentation
This pull request is based on the discussion in PR #35927.
Add a module-level note that `&&` and `||` are short-circuiting operators and not overloadable.
Add a simple `Scalar` example that lifts the `&` operator to a trivial struct tuple.
Make `BooleanVector` a struct tuple.
Derive `PartialEq` for `BooleanVector` instead of implementing it.
Adds a `fn main` wrapper so that the example can integrate with Rust Playground.
Guillaume Gomez
0c33197b90