Follow-up to 4c18af27, related to
tdf#96398, removing more client code. The following published
interfaces are removed:

com::sun::star::mozilla::XPluginInstance
com::sun::star::mozilla::XPluginInstanceNotifySink
com::sun::star::mozilla::XPluginInstancePeer
com::sun::star::mozilla::XPluginInstanceSyncPeer
com::sun::star::mozilla::XPluginWindowPeer
com::sun::star::plugin::PluginDescription
com::sun::star::plugin::PluginException
com::sun::star::plugin::PluginManager
com::sun::star::plugin::PluginMode
com::sun::star::plugin::PluginVariable
com::sun::star::plugin::XPlugin
com::sun::star::plugin::XPluginContext
com::sun::star::plugin::XPluginManager

Change-Id: I3818a23e0f46fd01bfe9be11b57f6a551c013441
Reviewed-on: https://gerrit.libreoffice.org/20780Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>
Tested-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>