graphics/openxr: new port - required for games/lwjgl3

OpenXR provides access to Augmented and Virtual Reality (XR-platforms).

This port required for build lwjgl 3, and lwjgl 3 required for Java
Minecraft Client 1.20.x run on FreeBSD without linux compatibility layer.

PR: 275279 269879 269900
Approved by: arrowd (mentor)
Differential Revision: https://reviews.freebsd.org/D44119