[RFC] Support for plug-in view renderering

[jwolffpsl]

We defined new interfaces which add support for plug-in view renderering. See https://github.com/fenderdigital/presonus-plugin-extensions/blob/main/ipslviewrendering.h
Support for these interfaces is implemented in Studio One 6.5.

As a proof of concept, we implemented plug-in side support for these interfaces in https://github.com/fenderdigital/vst3sdk

With Studio One 6.5, we added support for Linux. Studio One is a native Wayland application. As the VST3 SDK does not define a way for plug-ins to attach views to the host using Wayland, this interface can be used by plug-in developers to render simple user interfaces without explicit window system support.

See also #2 for additional interfaces which define a way for plug-ins to attach to a host application using Wayland.