Use unordered maps for VST3 plugin instances

The better algorithmic time complexity should help when using many (say,
hundreds) of instances of a single VST3 plugin.

src/common/communication/common.h

@@ -744,7 +744,7 @@ class AdHocSocketHandler {
 
         // This works the exact same was as `active_plugins` and
         // `next_plugin_id` in `GroupBridge`
-        std::map<size_t, Thread> active_secondary_requests{};
+        std::unordered_map<size_t, Thread> active_secondary_requests{};
         std::atomic_size_t next_request_id{};
         std::mutex active_secondary_requests_mutex{};
         accept_requests(

src/common/communication/vst3.h

@@ -526,7 +526,8 @@ class Vst3Sockets final : public Sockets {
      * would have one dedicated thread for handling function calls to these
      * interfaces, and then another dedicated thread just idling around.
      */
-    std::map<size_t, Vst3MessageHandler<Thread, AudioProcessorRequest>>
+    std::unordered_map<size_t,
+                       Vst3MessageHandler<Thread, AudioProcessorRequest>>
         audio_processor_sockets;
     std::mutex audio_processor_sockets_mutex;
 };

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

@@ -529,7 +529,7 @@ class Vst3PluginProxyImpl : public Vst3PluginProxy {
         /**
          * Memoizes `IEditController::getParameterInfo()`.
          */
-        std::map<int32, Steinberg::Vst::ParameterInfo> parameter_info;
+        std::unordered_map<int32, Steinberg::Vst::ParameterInfo> parameter_info;
     };
 
     /**

src/plugin/bridges/vst3.h

@@ -204,7 +204,7 @@ class Vst3PluginBridge : PluginBridge<Vst3Sockets<std::jthread>> {
      * `register_plugin_proxy()` in the constractor, and an instance is then
      * removed through a call to `unregister_plugin_proxy()` in the destructor.
      */
-    std::map<size_t, std::reference_wrapper<Vst3PluginProxyImpl>>
+    std::unordered_map<size_t, std::reference_wrapper<Vst3PluginProxyImpl>>
         plugin_proxies;
 
    private:

src/wine-host/bridges/vst3.h

@@ -440,7 +440,7 @@ class Vst3Bridge : public HostBridge {
      * will cause all pointers to it to get dropped and the object to be cleaned
      * up.
      */
-    std::map<size_t, InstanceInterfaces> object_instances;
+    std::unordered_map<size_t, InstanceInterfaces> object_instances;
     std::mutex object_instances_mutex;
 
     /**