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_opengl/opengl/juce_OpenGLContext.cpp

@@ -1224,6 +1224,8 @@ private:
         if (auto* cachedImage = CachedImage::get (*getComponent()))
             cachedImage->checkViewportBounds();
     }
+
+    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (Attachment)
 };
 
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