buildfix: adding .aszl to shader references

Signed-off-by: antonmic <56370189+antonmic@users.noreply.github.com>

Gems/Atom/Feature/Common/Assets/Shaders/PostProcessing/NewDepthOfFieldComposite.shader

@@ -1,5 +1,5 @@
 {
-    "Source" : "NewDepthOfFieldComposite",
+    "Source" : "NewDepthOfFieldComposite.azsl",
 
     "DepthStencilState" : 
     {

Gems/Atom/Feature/Common/Assets/Shaders/PostProcessing/NewDepthOfFieldDownsample.shader

@@ -1,5 +1,5 @@
 {
-    "Source" : "NewDepthOfFieldDownsample",
+    "Source" : "NewDepthOfFieldDownsample.azsl",
 
     "DepthStencilState" : {
         "Depth" : { "Enable" : false }

Gems/Atom/Feature/Common/Assets/Shaders/PostProcessing/NewDepthOfFieldFilterLarge.shader

@@ -1,5 +1,5 @@
 {
-    "Source" : "NewDepthOfFieldFilterLarge",
+    "Source" : "NewDepthOfFieldFilterLarge.azsl",
 
     "DepthStencilState" : {
         "Depth" : { "Enable" : false }

Gems/Atom/Feature/Common/Assets/Shaders/PostProcessing/NewDepthOfFieldFilterSmall.shader

@@ -1,5 +1,5 @@
 {
-    "Source" : "NewDepthOfFieldFilterSmall",
+    "Source" : "NewDepthOfFieldFilterSmall.azsl",
 
     "DepthStencilState" : {
         "Depth" : { "Enable" : false }

Gems/Atom/Feature/Common/Assets/Shaders/PostProcessing/NewDepthOfFieldTile3x3.shader

@@ -1,5 +1,5 @@
 {
-    "Source" : "NewDepthOfFieldTile3x3",
+    "Source" : "NewDepthOfFieldTile3x3.azsl",
 
     "DepthStencilState" : {
         "Depth" : { "Enable" : false }

Gems/Atom/Feature/Common/Assets/Shaders/PostProcessing/NewDepthOfFieldTileReduce.shader

@@ -1,5 +1,5 @@
 {
-    "Source" : "NewDepthOfFieldTileReduce",
+    "Source" : "NewDepthOfFieldTileReduce.azsl",
 
     "ProgramSettings" :
     {