Fix websocket server functions and add an example (#4107)

* Fix websocket server function

* Add websocket test

* add a websocket example

* fix clippy

packages/playwright-tests/fullstack/Cargo.toml

@@ -8,6 +8,7 @@ publish = false
 
 [dependencies]
 dioxus = { workspace = true, features = ["fullstack"] }
+futures.workspace = true
 serde = "1.0.218"
 tokio = { workspace = true, features = ["full"], optional = true }