RSE Hosts
Hosts, sometimes called "connections", are visible as the top level entities shown in the Remote Systems view.
Hosts are always created referencing a system type.
The system type determines the kinds of services that will be available to that host.
System types are defined by the org.eclipse.rse.core.systemTypes extension point, which lists the subsystemConfigurations
that are valid for type.
Once instantiated, hosts can be connected to their target systems.
This causes the connector services associated with
the subsystems belonging to that host to request connection.
Disconnect works similarly.
