Fully implement IParameterFinder

With this we're at VST 3.0.2 support.

src/plugin/bridges/vst3-impls/plug-view-proxy.cpp

@@ -157,3 +157,18 @@ Vst3PlugViewProxyImpl::checkSizeConstraint(Steinberg::ViewRect* rect) {
         return Steinberg::kInvalidArgument;
     }
 }
+
+tresult PLUGIN_API Vst3PlugViewProxyImpl::findParameter(
+    int32 xPos,
+    int32 yPos,
+    Steinberg::Vst::ParamID& resultTag /*out*/) {
+    const FindParameterResponse response =
+        bridge.send_message(YaParameterFinder::FindParameter{
+            .owner_instance_id = owner_instance_id(),
+            .x_pos = xPos,
+            .y_pos = yPos});
+
+    resultTag = response.result_tag;
+
+    return response.result;
+}

src/plugin/bridges/vst3-impls/plug-view-proxy.h

@@ -57,6 +57,12 @@ class Vst3PlugViewProxyImpl : public Vst3PlugViewProxy {
     tresult PLUGIN_API canResize() override;
     tresult PLUGIN_API checkSizeConstraint(Steinberg::ViewRect* rect) override;
 
+    // From `IParameterFinder`
+    tresult PLUGIN_API
+    findParameter(int32 xPos,
+                  int32 yPos,
+                  Steinberg::Vst::ParamID& resultTag /*out*/) override;
+
     /**
      * The `IPlugFrame` object passed by the host passed to us in
      * `IPlugView::setFrame()`. When the plugin makes a callback on the