This PR makes onnx sdpa export match the behavior of aten sdpa when boolean mask is used.
@justinchuby

```python
import onnxruntime as ort
import torch

class ScaledDotProductAttention(torch.nn.Module):
    def forward(self, query, key, value, attn_mask):
        return torch.nn.functional.scaled_dot_product_attention(query, key, value, attn_mask=attn_mask)

model = ScaledDotProductAttention()
attn_mask = torch.ones(2, 4, 8, 8).bool()  # boolean mask for attention
attn_mask[0, 0, 0, :] = False  # masking an entire row (padding token)
query = key = value = torch.randn(2, 4, 8, 16)
output = model(query, key, value, attn_mask)

torch.onnx.export(
    model,
    (query, key, value, attn_mask),
    "scaled_dot_product_attention.onnx",
    input_names=["query", "key", "value", "attn_mask"],
    output_names=["output"],
    dynamo=false, # or True,
)
ort_session = ort.InferenceSession("scaled_dot_product_attention.onnx")

np_inputs = {"query": query.numpy(), "key": key.numpy(), "value": value.numpy(), "attn_mask": attn_mask.numpy()}
onnx_outputs = ort_session.run(None, np_inputs)[0]

torch.testing.assert_close(output, torch.tensor(onnx_outputs), equal_nan=True)
```
fails the assertion because the ort model outputs nans.
Pull Request resolved: pytorch#159973
Approved by: https://github.com/xadupre, https://github.com/titaiwangms