fix(websocket): preserve failed connection error message

[raashish1601]

Summary

When a WebSocket connection fails before a parser is available, Undici had the failure reason in failWebsocketConnection() but WebSocket#onSocketClose() initialized the close reason from parser state only. That produced an ErrorEvent with an empty message.

This stores the failed-connection reason on the WebSocket handler and uses it when firing the error event, setting both error.message and the ErrorEvent.message field.

Fixes #4735.

Validation

• npm run lint -- lib/web/websocket/connection.js lib/web/websocket/websocket.js test/websocket/issue-4735.js
• npx borp --timeout 180000 -p "test/websocket/issue-4735.js"
• npx borp --timeout 180000 -p "test/websocket/issue-3546.js"
• npx borp --timeout 180000 -p "test/websocket/issue-4273.js"
• git commit pre-hook: npm run lint