Move QtQuick profiling to own profiler adapter

The QtQuick parts of the QML profiler service thus become a proper
global profiler which can be independently enabled and disabled.

Change-Id: Ifad03801cab2be66a264fc46fdebdae582fcc99b
Reviewed-by: Kai Koehne <kai.koehne@digia.com>
Add dedicated QML profiler and adapter

The remaining "profiling" parts of the QML profiler service are
engine specific and are best accessed through their own adapter.

Change-Id: Idb763104bdd80e4dabdf132ec1a496b9bc9f6f46
Reviewed-by: Kai Koehne <kai.koehne@digia.com>