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/fullstack-core/src/lib.rs

@@ -0,0 +1,30 @@
+// #![warn(missing_docs)]
+#![doc = include_str!("../README.md")]
+
+pub mod document;
+pub mod history;
+
+mod errors;
+mod loader;
+mod server_cached;
+mod server_future;
+mod streaming;
+mod transport;
+
+pub use crate::errors::*;
+pub use crate::loader::*;
+pub use crate::server_cached::*;
+pub use crate::server_future::*;
+pub use crate::streaming::*;
+pub use crate::transport::*;
+
+/// Error types and utilities.
+#[macro_use]
+pub mod error;
+pub use error::*;
+
+pub mod httperror;
+pub use httperror::*;
+
+#[derive(Clone, Default)]
+pub struct DioxusServerState {}