Repair etvk.vma_dep=instantiated to share VMA via 3.2.0 (#20225)

Summary:
Fixes the ExecuTorch Vulkan backend's `etvk.vma_dep=instantiated` mode
so the backend links a single, shared VulkanMemoryAllocator (VMA)
instead of instantiating its own. This is the prerequisite that lets a
binary link both ET Vulkan and another VMA consumer (e.g. IGL/compphoto)
without an `ld.lld: duplicate symbol: Vma*` collision.

Changes (both `fbcode` and `xplat` mirrors):
1. `backends/vulkan/targets.bzl`: repair the `etvk.vma_dep=instantiated`
path, which pointed at
`//third-party/VulkanMemoryAllocator/3.0.1:VulkanMemoryAllocatorInstantiated`
— a package that no longer exists at HEAD (only `3.2.0` remains), so the
mode was broken for everyone. Repoint it to
`3.2.0:VulkanMemoryAllocatorInstantiated`, the same target IGL/compphoto
already use, so VMA is linked exactly once.
2. `backends/vulkan/runtime/vk_api/memory/vma_api.h`: align the
`ETVK_USE_META_VMA` branch `VMA_VULKAN_VERSION` from `1002000` to
`1003000` to match the 3.2.0 instantiated lib's config
(`vk_mem_alloc_instantiated.h`) so struct layouts agree across
translation units and the pre-instantiated static lib (ABI safety).

Both changes only affect the opt-in `etvk.vma_dep=instantiated` mode
(which was already broken/unused), so default `xplat` builds and all
other ET consumers are byte-for-byte unchanged.

Differential Revision: D108337179

Co-authored-by: Xue Chen <xuechen@meta.com>

Author: blood-orange

backends/vulkan/runtime/vk_api/memory/vma_api.h

@@ -23,7 +23,10 @@
 #undef VMA_DYNAMIC_VULKAN_FUNCTIONS
 #define VMA_STATIC_VULKAN_FUNCTIONS 0
 #define VMA_DYNAMIC_VULKAN_FUNCTIONS 1
-#define VMA_VULKAN_VERSION 1002000
+// Must match the 3.2.0 VulkanMemoryAllocatorInstantiated config
+// (vk_mem_alloc_instantiated.h) so struct layouts agree across translation
+// units and the pre-instantiated static lib.
+#define VMA_VULKAN_VERSION 1003000
 
 #ifdef __clang__
 #pragma clang diagnostic push

backends/vulkan/targets.bzl

@@ -191,7 +191,7 @@ def define_common_targets(is_fbcode = False):
 
         if vma_dep == "instantiated":
             VK_API_DEPS = [
-                "fbsource//third-party/VulkanMemoryAllocator/3.0.1:VulkanMemoryAllocatorInstantiated",
+                "fbsource//third-party/VulkanMemoryAllocator/3.2.0:VulkanMemoryAllocatorInstantiated",
             ]
         else:
             VK_API_DEPS = [