VST3 wrapper: Audition doesn't call onSize

[refusesoftware]

I’m going to start a separate thread with a bug report for VST3 builds in Audition having no GUI.

Bug report: VST3 in Adobe Audition has no GUI

In Adobe Audition, the VST3 build does not display a GUI for the plug-in Editor. AU builds of the same project display their GUI correctly. Tested this with a couple different plug-in projects, on macOS (on Mojave and Catalina), with latest JUCE 6.0.8 (tried both master and develop branches). Here’s how the plug-in window looks in Audition for the VST3: [Screen Shot 2021-04-21 at 10.17.09 AM]