Update on "[ET][EZ] Enable operator<< for Half tensor data"

Useful for debugging `Half` i.e. `fp16` models, when we have `EValue`s that are `Half` dtype and we do the following:
```
std::cout << "===== INPUT =====" << std::endl;
for (EValue& v : inputs) {
  std::cout << v << std::endl;
}

std::cout << "===== OUTPUT =====" << std::endl;
for (EValue& v : outputs) {
  std::cout << v << std::endl;
}
```

## Before
```
===== INPUT =====
tensor(sizes=[1, 3, 96, 72], [<unhandled scalar type 5>])
===== OUTPUT =====
tensor(sizes=[1, 2, 96, 72], [<unhandled scalar type 5>])
```

## After
```
===== INPUT =====
tensor(sizes=[1, 3, 96, 72], [0.279785, 0.271484, 0.364746, ..., 0.150391, 0.836426, 0.019043])
===== OUTPUT =====
tensor(sizes=[1, 2, 96, 72], [18.2344, -10.0938, 1.35059, ..., -33.6875, 4.07422, -22.5312])
```

Differential Revision: [D57977366](https://our.internmc.facebook.com/intern/diff/D57977366/)

[ghstack-poisoned]

Author: jorgep31415

backends/vulkan/test/op_tests/cases.py

@@ -165,6 +165,7 @@ def get_avg_pool2d_inputs():
                 ]
 
     test_suite = VkTestSuite([tuple(tc) for tc in test_cases])
+    test_suite.dtypes = ["at::kFloat"]
     return test_suite