Initial unstyled language server short name in completions

Co-Authored-By: Kirill Bulatov <kirill@zed.dev>

crates/zed/src/languages/rust.rs

@@ -22,6 +22,10 @@ impl LspAdapter for RustLspAdapter {
         LanguageServerName("rust-analyzer".into())
     }
 
+    fn short_name(&self) -> &'static str {
+        "rust"
+    }
+
     async fn fetch_latest_server_version(
         &self,
         delegate: &dyn LspAdapterDelegate,