Limit Close frame to 125 bytes

All control frames should be limited to 125 frames.

https://tools.ietf.org/html/rfc6455#section-5.5



Task-number: QTBUG-62949
Change-Id: Id9b5a431faab6ff6edf7dc2e5c3525e999bc04ea
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>
Reviewed-by: Jesus Fernandez <Jesus.Fernandez@qt.io>