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/cli-harnesses/harness-fullstack-desktop-with-default/Cargo.toml

@@ -0,0 +1,19 @@
+[package]
+name = "harness-fullstack-desktop-with-default"
+version = "0.0.1"
+edition = "2021"
+license = "MIT OR Apache-2.0"
+publish = false
+
+[dependencies]
+dioxus = { workspace = true, features = ["fullstack"] }
+anyhow = { workspace = true, optional = true }
+
+
+[features]
+default=["desktop"]
+desktop=["dioxus/desktop", "has_anyhow"]
+has_anyhow=["dep:anyhow"]
+server=["dioxus/server"]
+
+    

packages/cli-harnesses/harness-fullstack-desktop-with-default/src/main.rs

@@ -0,0 +1,4 @@
+use dioxus::prelude::*;
+fn main() {
+    dioxus::launch(|| rsx! { "hello world!" })
+}