Windows: Fix DLL build

There were a few "ambiguous operator new/delete" errors that were due to
inheriting from a private base class that used the leak detector. These
errors are resolved by adding the leak detector to the derived classes.

JUCE_API was missing from a few useful types, notably the ARA hosting
types.

modules/juce_audio_devices/native/juce_Midi_windows.cpp

@@ -728,6 +728,8 @@ private:
     CriticalSection activeCollectorLock;
     ReferenceCountedArray<MidiInCollector> activeCollectors;
     Array<MidiOutHandle*> activeOutputHandles;
+
+    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (Win32MidiService)
 };
 
 Array<Win32MidiService::MidiInCollector*, CriticalSection> Win32MidiService::MidiInCollector::activeMidiCollectors;