feat(functions): Add support for meshopt v0.20 simplifyPoints()

[donmccurdy]

Related:

• https://github.com/donmccurdy/glTF-Transform/issues/1153

Remaining:

• [x] implementation and tests for indexed point clouds
• [x] benchmark changes to dequantize()

[donmccurdy]

• #1291 👈
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

Join @donmccurdy and the rest of your teammates on Graphite