Serialize all scalar types (#2414)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/2414

Adds all the [non-quantized scalar types from ATen Vulkan](https://github.com/pytorch/pytorch/blob/main/aten/src/ATen/native/vulkan/api/Types.h#L21-L26).
```
  _(uint8_t, VK_FORMAT_R8G8B8A8_UINT, Byte)              \
  _(int8_t, VK_FORMAT_R8G8B8A8_SINT, Char)               \
  _(int32_t, VK_FORMAT_R32G32B32A32_SINT, Int)           \
  _(bool, VK_FORMAT_R8G8B8A8_SINT, Bool)                 \
  _(unsigned short, VK_FORMAT_R16G16B16A16_SFLOAT, Half) \
  _(float, VK_FORMAT_FLOAT4, Float)                      \
```

Tensor images and buffers will now be created according to this `dtype`.

It's up to contributors to associate their shader to one of these dtypes, e.g., in [`all_shaders.yaml`](https://github.com/pytorch/executorch/blob/main/backends/vulkan/runtime/graph/ops/glsl/all_shaders.yaml#L32-L46).
```
image_to_nchw:
  ...
  generate_variant_forall:
    DTYPE:
      - VALUE: "half"
        SUFFIX: "half"
      - VALUE: "float"
        SUFFIX: "float"
  ...
```
ghstack-source-id: 218582139

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Reviewed By: SS-JIA

Differential Revision: D54873255

fbshipit-source-id: 9430e26b45e2b7fa464740aaee445db886f0f899