When a plugin broadcasts an event to instances there may be hosts and
instances in the cluster which does not have the plugin loaded. This
would cause an error to be logged for every instance which does not have
the plugin loaded.
Filter out broadcast events sent to hosts and instances such that
instances and hosts that does not have the event do not received them.
Move BaseControllerPlugin to controller/src/BaseControllerPlugin.ts
Move BaseInstancePlugin to host/src/BaseInstancePlugin.ts
Move BaseControlPlugin to ctl/src/BaseCtlPlugin.ts
Move BaseWebPlugin to web_ui/src/BaseWebPlugin.ts
This solves the circular package dependency problem of the base plugins
needing types that are available only in the dependencies to lib.