Allow to compile for other platforms

[bcardarella]

If RealityKit is included and you build for non-AVP Xcode crashes. With the multi-target projects it would make more sense if he addon didn't bomb in this scenario. That includes the enum being in addons

[carson-katri]

#9 adds support for iOS and macOS. That might fix the issue, not sure why Xcode would crash. You can also exclude dependencies for specific platforms in a multi-platform target if its a build issue.

[bcardarella]

it crashed on watchos I think