Update on "[ET-VK] Introduce vTensorPtr to prevent reference invalidation and remove get_val() API"

## Context

Currently when writing operators developers will save a reference to a `vTensor` retrieved from a `ComputeGraph`'s list of `values_` like so:

```
vTensor& vten = graph.get_val(vref).toTensor();
```

However, this is dangerous since if any values are added once the reference has been stored, `values_` which is a `std::vector` may have been resized and therefore have its contents moved, meaning the reference is now invalid.

To protect against this, this changeset introduces the `vTensorPtr` class which is a wrapper around a `vTensor*`.  When constructed, it will increment a counter in the `ComputeGraph` instance, and when destroyed it will decrement the counter. `ComputeGraph` cannot add any values while the counter is not zero.

Since `Value` can be converted to other non-trivial types, this changeset also removes the `get_val` function entirely to guard against unsafe behaviour.

Differential Revision: [D55984187](https://our.internmc.facebook.com/intern/diff/D55984187/)

[ghstack-poisoned]

Author: SS-JIA

backends/vulkan/runtime/graph/ops/impl/Sum.cpp

@@ -102,7 +102,8 @@ ValueRef add_node(
     const int dim,
     const bool keepdim,
     const api::ScalarType dtype = api::kFloat) {
-  std::vector<int64_t> output_size = calc_out_sizes(*(graph.get_tensor(input)), dim, keepdim);
+  std::vector<int64_t> output_size =
+      calc_out_sizes(*(graph.get_tensor(input)), dim, keepdim);
   return graph.add_tensor(output_size, dtype, api::kChannelsPacked);
 }
 

backends/vulkan/runtime/graph/ops/impl/utils/KernelUtils.cpp

@@ -150,7 +150,9 @@ std::vector<int64_t> calc_out_sizes_hw(
     return calc_transpose_out_sizes_hw(
         in_sizes, kernel_size, stride, padding, dilation, output_padding);
   } else {
-    const bool ceil_mode = graph.extract_scalar<bool>(args[3]);
+    const bool ceil_mode =
+        graph.val_is_bool(args[3]) ? graph.get_bool(args[3]) : false;
+
     return calc_out_sizes_hw(
         in_sizes, kernel_size, stride, padding, dilation, ceil_mode);
   }