Fixed Entity Shader emmissive

Makes sure that the emissiveAmount information is used correctly for a custom
shader, instead of using specular rgb information to generate the
emissiveness, which was incorrect

libraries/render-utils/src/simple.slf

@@ -75,7 +75,7 @@ void main(void) {
                 max(0, 1.0 - shininess / 128.0),
                 DEFAULT_METALLIC,
                 specular,
-                specular);
+                vec3(clamp(emissiveAmount, 0.0, 1.0)));
         } else {
             packDeferredFragment(
                 normal,