Function emit_toplevel 

pub fn emit_toplevel<'a, 'b, 'c>(
    s: &'c mut State<'a, 'b>,
    n: &str,
    ct: &'c Component<'b>,
)

In addition to the items emitted by [emit_component], mutate s to emit:

• a dummy Host type to reflect host functions
• a toplevel Guest trait that can be implemented to provide access to any guest state
• a hyperlight_guest_init function that registers all guest
• functions when given a type that implements the Guest trait