codify "platform" into resolution logic, server-fn/fullstack overhaul (#4596)

overhaul dioxus fullstack using a new implementation of server_fn

This PR is a complete rewrite of dioxus fullstack designed to improve compatibility with axum and to fix a number of compilation errors based on feature flag unification plumbing through macros.

packages/router/src/components/link.rs

@@ -7,7 +7,6 @@ use dioxus_core_macro::{rsx, Props};
 use dioxus_html::{
     self as dioxus_elements, ModifiersInteraction, MountedEvent, MouseEvent, PointerInteraction,
 };
-use dioxus_signals::{GlobalSignal, Owner, ReadableExt};
 
 use tracing::error;