Add websocket handler on server, connect from client

Additionally add /test handler that triggers server->client WS message

shared/src/lib.rs

@@ -14,7 +14,9 @@ pub struct SearchResult {
 }
 
 #[derive(Serialize, Deserialize, Debug)]
-pub struct Message {}
+pub enum WebsocketMessage {
+    RefreshMessages,
+}
 
 pub mod urls {
     pub const MOUNT_POINT: &'static str = "/api";