Feature request: Allow for both XR and non-XR code to co-exist in an application

[tcrass]

I'm working on an application that's supposed to be usable in both an XR and a non-XR mode. However

• If I run the application without setting up XR while SteamVR isn't running, I still get a dialog saying "OpenXR was requested, but failed to start", even though my XR setup code doesn't even get executed. The sheer presence of the OpenXR Tools plugin seems to pose a problem here.
• If I run the application without setting up XR, but with SteamVR running, I get tons of warnings saying "OpenXR: No viewport was marked with use_xr, there is no rendered output!" on the console.

It would be nice if interaction with the operating system's XR infrastructure only took place when actually required.