LYN-6793 [iOS] [asset_profile] 4 assets fail to process for iOS (#4268)

* LYN-6793 [iOS] [asset_profile] 4 assets fail to process for iOS
The issue was because the compression of ETC formats took too long.
Replaced all ETC and PVRTC formats with ASTC formats.
Update all pixel operation for formats with single R channel to align the change with R8.

Signed-off-by: Qing Tao <qingtao@amazon.com>

Gems/Atom/Asset/ImageProcessingAtom/Code/Source/Converters/PixelOperation.cpp

@@ -248,8 +248,8 @@ namespace ImageProcessingAtom
         {
             const uint8* data = buf;
             r = U8ToF32(data[0]);
-            g = 0.f;
-            b = 0.f;
+            g = r;
+            b = r;
             a = 1.f;
         }
 
@@ -333,8 +333,8 @@ namespace ImageProcessingAtom
         {
             const uint16* data = (uint16*)(buf);
             r = U16ToF32(data[0]);
-            g = 0.f;
-            b = 0.f;
+            g = r;
+            b = r;
             a = 1.f;
         }
 
@@ -418,8 +418,8 @@ namespace ImageProcessingAtom
         {
             const float* data = (float*)(buf);
             r = data[0];
-            g = 0.f;
-            b = 0.f;
+            g = r;
+            b = r;
             a = 1.f;
         }
 
@@ -485,8 +485,8 @@ namespace ImageProcessingAtom
         {
             const SHalf* data = (SHalf*)(buf);
             r = data[0];
-            g = 0.f;
-            b = 0.f;
+            g = r;
+            b = r;
             a = 1.f;
         }