rust: Test rust-analyzer binary after finding in PATH (#17951)

Release Notes:

- N/A

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/language/src/language.rs

@@ -285,6 +285,7 @@ pub trait LspAdapterDelegate: Send + Sync {
     async fn which(&self, command: &OsStr) -> Option<PathBuf>;
     async fn shell_env(&self) -> HashMap<String, String>;
     async fn read_text_file(&self, path: PathBuf) -> Result<String>;
+    async fn try_exec(&self, binary: LanguageServerBinary) -> Result<()>;
 }
 
 #[async_trait(?Send)]