buck2: Improve pop-up when the buck project is malformed

Summary:
When ELP is loading a buck project it does queries using buck.
Sometimes these fail, because the current state of the buck configuration files is invalid.
In that case, we show a pop-up suggesting that the user examine the buck dashboard, and provide a URL for this.

It is not always clear to the user that this is related to a malformed buck project, rather than a bug in ELP.

This diff tries to make it clearer.

Note that we unfortunately do not have the ability to use any kind of formatting in the displayed message.

Reviewed By: TD5

Differential Revision: D86510447

fbshipit-source-id: 57a93f829d37a8a4d7c8be88d6cf68adcf41c859

Author: alanz

crates/elp/src/server.rs

@@ -1803,9 +1803,13 @@ impl Server {
         }
         for (err, uri) in errors {
             if let Some(uri) = uri {
+                // It is not possible to put line breaks or other formatting in the message
+                let error_message = format!(
+                    "Look at `Details` in the buck UI for more information, there is likely an invalid BUCK file: {err}"
+                );
                 let params = lsp_types::ShowMessageRequestParams {
                     typ: lsp_types::MessageType::ERROR,
-                    message: err,
+                    message: error_message,
                     actions: Some(vec![MessageActionItem {
                         title: "Open Buck UI".to_string(),
                         properties: HashMap::from_iter(vec![(