Implement IComponent::getState()

With this the basic IComponent interface is fully implemented. Next will
be `IAudioProcessor` and `IConnectionPoint` as additions to IComponent.
We'll use the same `known_iids` mechanism as used in the plugin factory.

README.md

@@ -17,11 +17,13 @@ imcomplete list of things that still have to be done before this can be used:
 
 - Left to implement:
   - `YaHostApplicationHostImpl::createComponent`.
-  - The rest of `IComponent`'s functions
+  - `IAudioProcessor` and `IConnectionPoint` to supplement `IComponent`
+  - `IEditController{,2}`
   - All other mandatory interfaces
   - All other optional interfaces
 - Fully implemented:
   - `GetPluginFactory()` and `IPluginFactory{,2,3}`
+  - `IComponent`
 - Update the GitHub Actions workflows.
 - Update yabridgectl to handle buth VST2 and VST3 plugins.
 - Update all documentation to refer to VST2 and VST3 support separately, and