Print WebSocket errors when we get them (#2018)

* Print WebSocket errors when we get them

Previously, we eat them and ignore them, but now we'll seek out
and actively print error messages to stderr. We'd previously get a
websocket closed error, but we'll usually get an Error message over the
WebSocket before its closed on us.

Here's some example output during a crash

```
got ws error: WebSocket protocol error: Connection reset without closing handshake

Caused by:
    Connection reset without closing handshake
thread 'serial_test_cube_mm' panicked at tests/executor/main.rs:1136:10:
called `Result::unwrap()` on an `Err` value: engine: KclErrorDetails { source_ranges: [SourceRange([180, 188])], message: "Modeling command failed: websocket closed early" }
test serial_test_cube_mm ... FAILED
got error message: {
  "error_code": "bad_request",
  "message": "Too many active connections, only 2 allowed per user."
}
```

src/wasm-lib/kcl/src/engine/conn.rs

@@ -135,6 +135,9 @@ impl EngineConnection {
             loop {
                 match tcp_read.read().await {
                     Ok(ws_resp) => {
+                        for e in ws_resp.errors.iter().flatten() {
+                            println!("got error message: {e}");
+                        }
                         if let Some(id) = ws_resp.request_id {
                             responses_clone.insert(id, ws_resp.clone());
                         }