Update code to use new Three API

[KasperQd]

Description

Updates the code to use the new Three API. The old code used a deprecated API, which caused none of the projections but '360' to work.

This PR solves issues: #256, #268 and #266

Specific Changes proposed

• interact directly with uv attribute of geometry.
• remove conversion to BufferGeometry, since the geometry is already a child of BufferGeometry.

Requirements Checklist

• Feature implemented / Bug fixed
• If necessary, more likely in a feature request than a bug fix
  • Unit Tests updated or fixed (not needed here)
  • Docs/guides updated (not needed here)
• Reviewed by Two Core Contributors

[bbsimong]

I'm not a maintainer, but would like to see this merged.

There are similar changes in the WebXR PR (https://github.com/videojs/videojs-vr/pull/273/files#diff-598b75d6dc772eb13aa7141f35bb93046ae26c58a97e8647ecf7f74aec8ae93fR156). Unfortunately, it looks like that PR may be abandoned? I'm planning to open up a PR with our fork, but it will be rather large. Any smaller PRs that make our fork PR smaller would be very helpful.