A-Frame latest version support workaround

[kfarr]

Testing from current "known good" demo to latest version:

• 1.4.0 (working -- current a-frame example)
• 1.4.1 (working)
• 1.4.2 (working)
• 1.5.0 (NOT WORKING) - "AR mode" button does not display
• 1.5.0 Works with Fix: must include xr-mode-ui="XRMode: ar" in a-scene
• 1.6.0 Works with Fixes: - must include xr-mode-ui="XRMode: ar" in a-scene, must update environment component to 1.5.x
• 1.7.0 Works (with 1.6.0 Fixes)
• 1.7.1 Works (with 1.6.0 Fixes)

Relevant item from A-Frame Changelog from 1.5.0:

• vr-mode-ui component renamed to xr-mode-ui

[kfarr]

https://github.com/Variant3d/launch-examples/pull/3/commits/c2642be3eb4b46ebff88fd3a46ab0b52f379c41a