GLB import to Editor ignores KHR_materials_pbrSpecularGlossiness

[willeastcott]

While the engine's GLB parser can load GLB's that use the archived extension KHR_materials_pbrSpecularGlossiness, the Editor import process skips over this extension data.

[willeastcott]

Another report of this problem:

https://forum.playcanvas.com/t/using-sketchfab/39397/4

Please can we fix this ASAP?

[willeastcott]

Fixed by @slimbuck