Add a way to not double box items

[krishna-selectstar]

I'm currently using ouroboros store some strings with their parsed equivalents like this:

#[self_referencing]
struct Data {
    text: String,
    #[covariant]
    #[borrows(text)]
    parsed: Ast<'this>
}

And I would like to avoid double boxing the string. Is there a way that I could use AliasedString, add an annotation and have it be unboxed, like this?

#[self_referencing]
struct Data {
    #[unboxed]
    text: AliasedString,
    #[covariant]
    #[borrows(text)]
    parsed: Ast<'this>
}