[dawn][vk] Support storage texel buffers

Implements `TexelBufferViewVk` wrapping `VkBufferView`, wires it into
bind groups and descriptor set updates, and maps `TEXEL_BUFFER` buffer
usage to `VK_BUFFER_USAGE_STORAGE_TEXEL_BUFFER_BIT`.

Texel buffer bindings are remapped through `GenerateBindingRemapping`
in `TintUtils.h` by injecting into the `storage_texture` sub-map of
`tint::Bindings`. This is a workaround because `tint::Bindings` has no
dedicated `texel_buffer` field yet. The `BindingRemapper` transform is
type-agnostic — it remaps any WGSL variable whose `binding_point`
appears in the map regardless of descriptor type — so the remapping is
correct. Without it, texel buffers would keep their original WGSL
`@binding` numbers in SPIR-V, diverging from their `BindingIndex` in
`VkDescriptorSetLayout` whenever a binding type that sorts before
`TexelBuffer` (e.g. `StorageTexture`) occupies an earlier slot.

Bug: 382544164
Change-Id: I889230b2bc1e2d6cfb3d599a020c6735d9646673
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/258500
Reviewed-by: James Price <jrprice@google.com>
Reviewed-by: Diego Rodrigues <diejorarr@gmail.com>
Reviewed-by: Loko Kung <lokokung@google.com>
Commit-Queue: James Price <jrprice@google.com>