Add "Triangulate Faces" option to FBX export

I noticed the FBX export was missing a triangulation option seen in other software and other Blender exporters such as .obj.

This feature is rather useful for example for ensuring consistent normal map baking in third party software, where tangent space gets easily messed up with tools using mikktspace that depends on triangulation choices.

This patch adds a "Triangulate Faces" option in the export options similarly to what the Wavefront OBJ exporter has. Diff-wise it's rather simple by reusing the temporary mesh creation from "Apply Modifiers".

Reviewed By: mont29

Differential Revision: https://developer.blender.org/D14352