Improve yoga/assimp importing success rate

[Breush]

Currently, yoga is not able to import a glb, as the check for the format wants to make sure that the filename ends with .glb (and it does not because assimp reads memory).

Provide a pHint argument to readFileFromMemory: http://assimp.sourceforge.net/lib_html/class_assimp_1_1_importer.html#a9b3c5e8b1042702f449e84a95b3324f6

Generate it from lowercased the filename's extension (if any).