Convert LUClusterConfigQuery to query2

The main intention of this patch is to make it possible to retrieve
cluster tags via query2. While at it I decided to convert
LUClusterConfigQuery right away. Some of the values returned by
LUClusterQuery are also included, but the conversion of LUClusterQuery
is not yet complete.

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>