Add missing particle texture references

Author: Choonster

src/main/resources/assets/testmod3/models/block/empty.json

@@ -1 +1,5 @@
-{}
+{
+  "textures": {
+    "particle": "minecraft:missingno"
+  }
+}

src/main/resources/assets/testmod3/models/block/pressure_plate_down_with_transforms.json

@@ -1,5 +1,8 @@
 {
   "parent": "minecraft:block/thin_block",
+  "textures": {
+    "particle": "#texture"
+  },
   "elements": [
     {
       "faces": {

src/main/resources/assets/testmod3/models/block/template_fullbright.json

@@ -42,6 +42,6 @@
     }
   ],
   "textures": {
-    "#particle": "#all"
+    "particle": "#all"
   }
 }