Add validation for supported version of cluster state metadata on node join

[imotov]

In #21830 we made sure that nodes cannot join a cluster that has indices created by nodes with incompatible versions. Since cluster metadata (such as custom metadata, index templates, etc) might be also incompatible with certain version of nodes, we need to add another check that will ensure that cluster metadata is compatible with nodes that can join the cluster.

In other words we need to ensure that

1. a 6.0 node cannot join the cluster that has pre-5.6 nodes.
2. ones a 6.0 node joins the cluster and updates the cluster metadata, we need to make sure that pre-5.6 nodes cannot join this cluster.

[imotov]

That is handled by #25770. Closing.