@sensitive trait isn't respected when applied to containing shape

[aajtodd]

The sensitive trait can be applied to:

:not(:is(service, operation, resource, member))
any shape that isn't a service, operation, resource, or member

e.g. applied to a structure shape

string Baz
            
@sensitive
structure Foo {
    bar: Baz,
    @documentation("Member documentation")
    baz: Baz,
    qux: String
}

This is not handled correctly when generating toString() implementations