Reland "Add vulkan format image fallback for R16G16B16"

Suppressed misbehaving trace test in https://crrev.com/c/4317088

This is a reland of commit 71f6d54c8d

Original change's description:
> Add vulkan format image fallback for R16G16B16
>
> This change adds a vulkan format image mapping fallback from R16G16B16
> to R16G16B16A16, R32G32B32_FLOAT and R32G32B32A32_FLOAT for both
> UNORM and SNORM variants.
>
> This is done because in Chrome we want to use R16/RG16 formats which
> are exposed to Skia over the EXT_texture_norm16. Currently,
> EXT_texture_norm16 requires RGB16_EXT which if not present is not
> supported even if R16_EXT and RG16_EXT are supported. This fallback
> helps us support R16/RG16 as well over RGBA16.
>
> It also updates validationES checks for GL_RGBA signed and unsigned
> normalized checking if type is GL_SHORT or GL_UNSIGNED_SHORT.
>
> It adds a method LoadToFloat that allows a type (GLushort or GLshort)
> to be loaded into float format types. This is then used as part of
> fallbacks for load_functions_data.json.
>
> Bug: None
> Change-Id: I5c6879cd2ed5dd6e3440877f4891f269d96d88a1
> Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4294694
> Reviewed-by: Vasiliy Telezhnikov <vasilyt@chromium.org>
> Reviewed-by: Geoff Lang <geofflang@chromium.org>
> Commit-Queue: Geoff Lang <geofflang@chromium.org>

Bug: None
Change-Id: I101dd9e8c62e6794692c9f89c4944297e195f710
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4317089
Reviewed-by: Cody Northrop <cnorthrop@google.com>
Auto-Submit: Roman Lavrov <romanl@google.com>
Commit-Queue: Cody Northrop <cnorthrop@google.com>

scripts/code_generation_hashes/DXGI_format.json

@@ -1,6 +1,6 @@
 {
   "src/libANGLE/renderer/angle_format.py":
-    "0660cb3dfc7f5d29b099c94ed78f63a3",
+    "601bfb757e052c50ac8f4cb4e0b58eb5",
   "src/libANGLE/renderer/angle_format_map.json":
     "4c09d19204afa53cd9d137bb4edbabb1",
   "src/libANGLE/renderer/dxgi_format_data.json":