Avoid recreating QVariantLists when extracted from a QVariant

Avoid recreating QVariantLists when extracted from a QVariant

Wrapping a QVariantList in a QVariant to pass it to QML would
trigger a deep copy each time QML would try to access elements
in the list (specifically in QQmlListAccessor::at).

This reverts a part of 8c4deff51c8064f5a15cae0342bfa66b6663662b
by specifying the associative array conversions explicitly without
including the current type in the list of types to convert through
an iteration.

Task-number: QTBUG-41403
Change-Id: If9fddfe6d36f789ac4aa61a7c32677cd1dd077d8
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>