Werk #13530: FIX node and cluster data source consistency validation

While creating a cluster the configured data sources are checked against each node. If they are not the same the cluster cannot be saved.

Previously only the tags IDs "agent" or "snmp" were checked. If for example a node has the data source "Checkmk agent" then the cluster must have the same datasource. Otherwise the error "The node NODENAME has datasources and 'agent' while the cluster has datasources and 'no-agent'." was display.

Now auxilary tags are also involved which may be set through other tags or tag groups, eg. the tag "cmk-agent" implicilty sets the auxilary tag "tcp". This auxilary tag may also be set through custom tags or tag groups.

Details: The tags "cmk-agent", "all-agents" and "special-agents" contain the auxilary tag "tcp" and belong to the default tag group "agent". During validation the exact values "all-agents" and "special-agents" are checked and after these "tcp" is taken into account. This behaviour is equivalent to the decision which data sources are added to a host.

Regarding the tag group "snmp_ds" the validation checks the tag values "snmp-v1", "snmp-v2" and the auxilary tag "snmp".

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