Author XR in XR

For setup and usage instructions, refer to the documentation

Dependencies:

• com.unity.xrtools.module-loader
• com.unity.xrtools.utils
• com.unity.list-view-framework
• com.unity.xrtools.spatial-hash
• com.unity.xr.legacyinputhelpers
• com.unity.xr-line-renderer
• com.unity.timeline
• com.unity.textmeshpro