Update SetBindGroup dynamic offsets to uint32_t

In WebGPU these are uint32_t because Vulkan accepts at most a 32-bit
unsigned integer.

Bug: dawn:22
Change-Id: Ia61cd710f80c19135ac215a9a93ef9a8f683bac2
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/12942
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>

examples/Animometer.cpp

@@ -159,7 +159,7 @@ void frame() {
         pass.SetPipeline(pipeline);
 
         for (size_t i = 0; i < kNumTriangles; i++) {
-            uint64_t offset = i * sizeof(ShaderData);
+            uint32_t offset = i * sizeof(ShaderData);
             pass.SetBindGroup(0, bindGroup, 1, &offset);
             pass.Draw(3, 1, 0, 0);
         }