Added-fox-face.sfb into res/raw directory

[Zeuskartik]

com.google.ar.sceneform.samples.augmentedfaces/AugmentedFacesActivity line number 73-
.setSource(this, R.raw.fox_face)
The res/raw directory was missing and also the fox-face,sfb.
Created fox-face.sfb from fox-face.fbx and added it to the res/raw folder so that the AugmentedFacesActivity,java isn't buggy anymore due to missing resource.

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[Zeuskartik]

@googlebot I signed it!

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[SimonMarquis]

@Zeuskartik I don't think this is what's actually expected.
Instead, this .sfb file will be automatically generated by the sceneform plugin during the initial build on your machine.