Re-export the axum feature flag under "server" (#2786)

* re-export the axum feature flag under "server"
* remove the axum prefix from all the fullstack examples

packages/fullstack/examples/hello-world/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "fullstack-hello-world-example"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+dioxus = { workspace = true, features = ["fullstack"]}
+serde = "1.0.159"
+simple_logger = "4.2.0"
+tracing-wasm = "0.2.1"
+tracing = { workspace = true }
+tracing-subscriber = "0.3.17"
+reqwest = { workspace = true }
+
+[features]
+default = []
+server = ["dioxus/axum"]
+web = ["dioxus/web"]