Various fixes in example

[mrxz]

Description:
Found several small mistakes in the examples.

Changes proposed:

• Update usages of vr-mode-ui to xr-mode-ui
• Omit crossorigin="anonymous" on <a-asset-item> tags as this has no effect
• Remove components/attributes that no longer exist or don't do anything (auto-enter-vr and opacity on <a-entity>)
• Change filter to filterLabels as the former doesn't exist on the real-world-meshing component
• Fix typo accidentally using , as property delimiter instead of ;

[dmarcos]

Thanks so much. just a small change

[mrxz]

Didn't know a new version of the environment component was already out. I took the liberty to update all instances in the examples as it's needed for proper colour management. Did end up removing the script from the mixed-reality/anchor example as it didn't use the environment in any way.

[dmarcos]

Thanks!