VST3 interfaces

See docs/vst3.md for more information on how the serialization works.

The following interfaces are not yet implemented:

Every interface introduced after VST 3.1.0, although most of the VST 3.5.0 interfaces have already been implemented
The Presonus extensions, although most of these things seem to overlap with newer VST3 interfaces

VST3 plugin interfaces are implemented as follows:

yabridge class	Included in	Interfaces
`YaPluginFactory`		`IPluginFactory`, `IPluginFactory2`, `IPluginFactory3`
`Vst3ConnectionPointProxy`		`IConnectionPoint` through `YaConnectionPoint`
`Vst3PlugViewProxy`		All of the below:
`YaParameterFinder`	`Vst3PlugViewProxy`	`IParameterFinder`
`YaPlugView`	`Vst3PlugViewProxy`	`IPlugView`
`Vst3PluginProxy`		All of the below:
`YaAudioPresentationLatency`	`Vst3PluginProxy`	`IAudioPresentationLatency`
`YaAudioProcessor`	`Vst3PluginProxy`	`IAudioProcessor`
`YaComponent`	`Vst3PluginProxy`	`IComponent`
`YaConnectionPoint`	`Vst3PluginProxy`	`IConnectionPoint`
`YaEditController`	`Vst3PluginProxy`	`IEditController`
`YaEditController2`	`Vst3PluginProxy`	`IEditController2`
`YaEditControllerHostEditing`	`Vst3PluginProxy`	`IEditControllerHostEditing`
`YaKeyswitchController`	`Vst3PluginProxy`	`IKeyswitchController`
`YaMidiMapping`	`Vst3PluginProxy`	`IMidiMapping`
`YaNoteExpressionController`	`Vst3PluginProxy`	`INoteExpressionController`
`YaPluginBase`	`Vst3PluginProxy`	`IPluginBase`
`YaProgramListData`	`Vst3PluginProxy`	`IProgramListData`
`YaUnitData`	`Vst3PluginProxy`	`IUnitData`
`YaUnitInfo`	`Vst3PluginProxy`	`IUnitInfo`

VST3 host interfaces are implemented as follows:

The following host interfaces are passed as function arguments and are thus also implemented for serialization purposes:

yabridge class	Interfaces	Notes
`YaAttributeList`	`IAttributeList`
`YaContextMenuTarget`	`IContextMenuTarget`	Used in `YaContextMenu` to proxy specific menu items
`YaEventList`	`IEventList`	Comes with a lot of serialization wrappers around the related structs
`YaMessage`	`IMessage`
`YaMessagePtr`	`IMessage`	Should be used in inter process communication to exchange messages
`YaParameterChanges`	`IParameterChanges`
`YaParamValueQueue`	`IParamValueQueue`
`VectorStream`	`IBStream`	Used for serializing data streams

And finally YaProcessData uses the above along with YaAudioBusBuffers to wrap around ProcessData.