Add a toggle for Fast GI Approximation in the header of the panel,
following Cycles layout.
Move the `Max Roughness` setting inside the panel, and rename to
Threshold.
Since Fast GI Approximation only has any effect when Threshold/
Max Roughness is below the max (1.0), gray out the rest of the
panel when at that value.
Co-authored-by: Clément FOUCAULT <foucault.clem@gmail.com>
Pull Request: https://projects.blender.org/blender/blender/pulls/125452
000d34c398