Implement IAudioProcessor::process()

With this the entire `IAudioProcessor` interface has been implemented
and in theory it should now be possible to process audio and events.
Logging for these requests still has to be implemented separately.

src/common/serialization/vst3.h

@@ -75,7 +75,7 @@ using ControlRequest = std::variant<YaComponent::Construct,
                                     YaComponent::GetLatencySamples,
                                     YaComponent::SetupProcessing,
                                     YaComponent::SetProcessing,
-                                    // TODO: YaComponent::Process
+                                    YaComponent::Process,
                                     YaComponent::GetTailSamples,
                                     YaPluginFactory::Construct,
                                     YaPluginFactory::SetHostContext>;