Update Primitive for AddAnyAttr on AnyView

[geoffreygarrett]

When AddAnyAttr is officially working in Leptos 0.7, the current working design for the asChild API would benefit in some ergonomics if Children and ChildrenFn are used instead of their typed variants. A feature flag in the relevant components where it would make a difference would allow one to patch while it's being merged.

• another try at adding AddAnyAttr to AnyView leptos-rs/leptos#3458

Feature flag where relevant: any-view-any-attr