Feat: support refraction with BTDF

[zhuxudong]

Please check if the PR fulfills these requirements

• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

Feature.

What is the current behavior? (You can also link to an open issue here)

BRDF is not supported in light transmission with refraction.

What is the new behavior (if this is a feature change)?

support BTDF with refraction in light transmission and KHR_materials_volume plugin.

[codecov-commenter]

Codecov Report

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