Split off IComponent and create a monolithic class

We can now use implement all VST3 plugin interfaces through this class,
check whether the object from the plugin also supports these classes,
and then conditionally allow casting to the supported classes. This
should give us a one-to-one proxy of the original object.

src/common/serialization/vst3.h

@@ -23,8 +23,8 @@
 #include "../configuration.h"
 #include "../utils.h"
 #include "common.h"
-#include "vst3/component.h"
 #include "vst3/plugin-factory.h"
+#include "vst3/plugin-monolith.h"
 
 // Event handling for our VST3 plugins works slightly different from how we
 // handle VST2 plugins. VST3 does not have a centralized event dispatching
@@ -57,8 +57,16 @@ struct WantsConfiguration {
  * encodes the information we request or the operation we want to perform. A
  * request of type `ControlRequest(T)` should send back a `T::Response`.
  */
-using ControlRequest = std::variant<YaComponent::Construct,
-                                    YaComponent::Destruct,
+using ControlRequest = std::variant<YaPluginMonolith::Construct,
+                                    YaPluginMonolith::Destruct,
+                                    YaAudioProcessor::SetBusArrangements,
+                                    YaAudioProcessor::GetBusArrangement,
+                                    YaAudioProcessor::CanProcessSampleSize,
+                                    YaAudioProcessor::GetLatencySamples,
+                                    YaAudioProcessor::SetupProcessing,
+                                    YaAudioProcessor::SetProcessing,
+                                    YaAudioProcessor::Process,
+                                    YaAudioProcessor::GetTailSamples,
                                     YaComponent::SetIoMode,
                                     YaComponent::GetBusCount,
                                     YaComponent::GetBusInfo,
@@ -67,14 +75,6 @@ using ControlRequest = std::variant<YaComponent::Construct,
                                     YaComponent::SetActive,
                                     YaComponent::SetState,
                                     YaComponent::GetState,
-                                    YaComponent::SetBusArrangements,
-                                    YaComponent::GetBusArrangement,
-                                    YaComponent::CanProcessSampleSize,
-                                    YaComponent::GetLatencySamples,
-                                    YaComponent::SetupProcessing,
-                                    YaComponent::SetProcessing,
-                                    YaComponent::Process,
-                                    YaComponent::GetTailSamples,
                                     YaPluginBase::Initialize,
                                     YaPluginBase::Terminate,
                                     YaPluginFactory::Construct,