Reland "D3D12: Stage BindGroups on CPU descriptor heaps."

This reverts commit c7f454c241
and relands commit 2479860e4b.

> D3D12: Stage BindGroups on CPU descriptor heaps.
>
> Instead of directly populating GPU heaps, pre-encoded
> BindGroups are staged on CPU heaps then copied over
> to the GPU. Non-shader visible allocators are stored
> on the BGL, which hands out fixed-size chunks to
> simplify memory managment. To enable memory re-use,
> CPU allocations are tied to the lifetime of BindGroup
> objects.

Reason for revert: We can reland this CL now that the CTS suppression merged.

Note: Adds validation to ensure binding size > 0.

Bug: dawn:155
Bug: dawn:375
Change-Id: I75b9773bbb7c70bcea803a7ad8b6480d21ea90f7
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/18904
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Kai Ninomiya <kainino@chromium.org>

src/common/Math.cpp

@@ -19,6 +19,7 @@
 
 #include <algorithm>
 #include <cmath>
+#include <limits>
 
 #if defined(DAWN_COMPILER_MSVC)
 #    include <intrin.h>
@@ -152,3 +153,10 @@ float SRGBToLinear(float srgb) {
         return std::pow((srgb + 0.055f) / 1.055f, 2.4f);
     }
 }
+
+uint64_t RoundUp(uint64_t n, uint64_t m) {
+    ASSERT(m > 0);
+    ASSERT(n > 0);
+    ASSERT(m <= std::numeric_limits<uint64_t>::max() - n);
+    return ((n + m - 1) / m) * m;
+}