tools/mesh-cfgclient: Save provisioner info

tools/mesh-cfgclient: Save provisioner info

This adds "provisioners" property to the config database.
The property includes the provisioner's name, UUID of the provisioner
device (corresponds to the local node), allocated unicast, group and
scene ranges.
The current implementation limitations:
- only one provisioner in the mesh network is supported,
- the unicast range is assumed to be contiguous,
- the group range is assumed to be contiguous,
- no support for scenes (empty array).

Signed-off-by: Anuj Jain <anuj01.jain@samsung.com>
Signed-off-by: Ayush Garg <ayush.garg@samsung.com>