Allow indirect IConnectionPoint connections

This is needed to support Ardour. These extra hops and serialization
steps will probably hurt performance, but outside of some huge hacks (to
connect the components directly anyways) there's not much else we can
do.

src/common/serialization/vst3/connection-point-proxy.cpp

@@ -16,13 +16,6 @@
 
 #include "connection-point-proxy.h"
 
-Vst3ConnectionPointProxy::ConstructArgs::ConstructArgs() {}
-
-Vst3ConnectionPointProxy::ConstructArgs::ConstructArgs(
-    Steinberg::IPtr<Steinberg::FUnknown> object,
-    size_t owner_instance_id)
-    : owner_instance_id(owner_instance_id), connection_point_args(object) {}
-
 Vst3ConnectionPointProxy::Vst3ConnectionPointProxy(const ConstructArgs&& args)
     : YaConnectionPoint(std::move(args.connection_point_args)),
       arguments(std::move(args)){FUNKNOWN_CTOR}