adding double sided back test and updated primitive uv texture (#4022)

tests/validation/config.json

@@ -183,18 +183,18 @@
       "referenceImage": "customRTT.png"
     },
     {
-      "title": "GLTF Buffer Interleaved",
-      "scriptToRun": "/Demos/GLTFTests/index.js",
-      "functionToCall": "createBufferInterleavedScene",
-      "referenceImage": "gltfBufferInterleaved.png"
-    },
-    {
       "title": "GLTF Normals",
       "scriptToRun": "/Demos/GLTFNormals/index.js",
       "functionToCall": "createScene",
       "referenceImage": "gltfnormals.png"
     },
     {
+      "title": "GLTF Buffer Interleaved",
+      "scriptToRun": "/Demos/GLTFTests/index.js",
+      "functionToCall": "createBufferInterleavedScene",
+      "referenceImage": "gltfBufferInterleaved.png"
+    },
+    {
       "title": "GLTF Material",
       "scriptToRun": "/Demos/GLTFTests/index.js",
       "functionToCall": "createMaterialScene",
@@ -219,6 +219,12 @@
       "referenceImage": "gltfMaterialDoubleSided.png"
     },
     {
+      "title": "GLTF Material Double Sided (Back)",
+      "scriptToRun": "/Demos/GLTFTests/index.js",
+      "functionToCall": "createMaterialDoubleSidedBackScene",
+      "referenceImage": "gltfMaterialDoubleSidedBack.png"
+    },
+    {
       "title": "GLTF Material Mixed",
       "scriptToRun": "/Demos/GLTFTests/index.js",
       "functionToCall": "createMaterialMixedScene",