[ET-VK][ez] enabling fp64->fp32 converison for vulkan compatibility

# Context

We need this conversion so that certain operators can handle floating point values that need to be 64bit. This is predominantly applicable to choose_qparams.tensor where it expects a 64bit output.

# Changes

Simply adding an additional conversion for float64 to vulkan fp32.

Differential Revision: [D77746137](https://our.internmc.facebook.com/intern/diff/D77746137/)

[ghstack-poisoned]

Author: morelos

backends/vulkan/serialization/vulkan_graph_builder.py

@@ -79,6 +79,10 @@ def get_vk_datatype(torch_dtype: torch.dtype) -> vk_graph_schema.VkDataType:
         # Narrowing conversion for index tensor produced by max_poolNd_with_indices.
         elif torch_dtype == torch.int64:
             return vk_graph_schema.VkDataType.INT32
+        # Narrowing conversion for float64 (double) to float32 for Vulkan compatibility
+        elif torch_dtype == torch.float64:
+            return vk_graph_schema.VkDataType.FLOAT32
+
         else:
             raise AssertionError(f"Invalid dtype for vulkan_preprocess ({torch_dtype})")