Coalesce server group view and Infinispan/JGroups view

Currently the console is using the server-group knowledge (i.e. which host/servers belong to a specific group). While that is definitely the "ideal" situation, we also need to ensure that it corresponds to the "actual" cluster as known to Infinispan/JGroups. This information should be then used to present the user with appropriate warnings if necessary.

For each container %c in each server %s in the server group we need to extract the "members" property:

/host=%h/server=%s/subsystem=datagrid-infinispan/cache-container=%c:read-attribute(name=members)

This returns a list of server names (in the form %h:%s).

This is how we should use the information (in combination with the existing "cluster-availability" property information from the coordinator):

1. If the server-group list coincides with the container members of all nodes, all is good: the cluster is healthy, all nodes are up and running
2. If all of the container members contain the SAME subset of the server group, but the missing members are in the STOPPED or STARTING state, everything could be normal: we should depend on the coordinator's "cluster-availability" to tell us if the cluster is unhealthy.
3. If the container members differ between each other and with the server group view, and all these servers are in RUNNING we have a potential split brain or a cluster which is not formed correctly.

The above deduction should determine not only the label / colour-coding we place in the view header (AVAILABLE, DEGRADED, etc) but also some of the view content: in both the cluster nodes view and the cache nodes view we need to group / sort by membership, so that we clearly show split clusters and stopped nodes.