QmlProfiler: relay context menu from trace view to parent widget

As QQuickView is a window with its own event handling, disconnected
from the main window, we need to relay relevant events manually.

Task-number: QTCREATORBUG-11535

Change-Id: If316225ecc01ddc4255c209d7df70a9cee812596
Reviewed-by: Kai Koehne <kai.koehne@digia.com>