[torchlib] Register aten::__lshift__ and __rshift__ (#2102)

Tested with

```py
import math
import torch

class Gray(torch.nn.Module):
    nbits: int = 32

    def forward(self, gray: torch.Tensor):
        shifts = [(0x1 << i) for i in range((math.ceil(math.log(self.nbits, 2)) - 1), -1, -1)]
        for shift in shifts:
            gray ^= gray >> shift

        return gray


onnx_program = torch.onnx.export(
    Gray(),  # model to export
    (torch.randint(0, 100, [100], dtype=torch.long)),  # inputs of the model,
    dynamo=True,  # True or False to select the exporter to use,
)

print(onnx_program)
```

Fixes pytorch/pytorch#149083

Author: justinchuby

onnxscript/function_libs/torch_lib/ops/core.py

@@ -1243,6 +1243,7 @@ def aten_bitwise_and(self: TInt, other: TInt) -> TInt:
         "aten::bitwise_left_shift.Tensor_Scalar",
         "aten::bitwise_left_shift.Scalar_Tensor",
         "_operator::__lshift__",
+        "aten::__lshift__.Scalar",
     ),
     trace_only=True,
 )
@@ -1263,6 +1264,7 @@ def aten_bitwise_left_shift_int16(self: INT16, other: INT16) -> INT16:
         "aten::bitwise_left_shift.Tensor_Scalar",
         "aten::bitwise_left_shift.Scalar_Tensor",
         "_operator::__lshift__",
+        "aten::__lshift__.Scalar",
     ),
     trace_only=True,
 )
@@ -1283,6 +1285,7 @@ def aten_bitwise_left_shift_int32(self: INT32, other: INT32) -> INT32:
         "aten::bitwise_left_shift.Tensor_Scalar",
         "aten::bitwise_left_shift.Scalar_Tensor",
         "_operator::__lshift__",
+        "aten::__lshift__.Scalar",
     ),
     trace_only=True,
 )
@@ -1303,6 +1306,7 @@ def aten_bitwise_left_shift_int64(self: INT64, other: INT64) -> INT64:
         "aten::bitwise_left_shift.Tensor_Scalar",
         "aten::bitwise_left_shift.Scalar_Tensor",
         "_operator::__lshift__",
+        "aten::__lshift__.Scalar",
     ),
     trace_only=True,
 )
@@ -1347,6 +1351,7 @@ def aten_bitwise_or(self: TInt, other: TInt) -> TInt:
         "aten::bitwise_right_shift.Tensor_Scalar",
         "aten::bitwise_right_shift.Scalar_Tensor",
         "_operator::__rshift__",
+        "aten::__rshift__.Scalar",
     )
 )
 def aten_bitwise_right_shift_int16(self: INT16, other: INT16) -> INT16:
@@ -1377,6 +1382,7 @@ def aten_bitwise_right_shift_int16(self: INT16, other: INT16) -> INT16:
         "aten::bitwise_right_shift.Tensor_Scalar",
         "aten::bitwise_right_shift.Scalar_Tensor",
         "_operator::__rshift__",
+        "aten::__rshift__.Scalar",
     )
 )
 def aten_bitwise_right_shift_int32(self: INT32, other: INT32) -> INT32:
@@ -1407,6 +1413,7 @@ def aten_bitwise_right_shift_int32(self: INT32, other: INT32) -> INT32:
         "aten::bitwise_right_shift.Tensor_Scalar",
         "aten::bitwise_right_shift.Scalar_Tensor",
         "_operator::__rshift__",
+        "aten::__rshift__.Scalar",
     )
 )
 def aten_bitwise_right_shift_int64(self: INT64, other: INT64) -> INT64:
@@ -1440,6 +1447,7 @@ def aten_bitwise_right_shift_int64(self: INT64, other: INT64) -> INT64:
         "aten::bitwise_right_shift.Tensor_Scalar",
         "aten::bitwise_right_shift.Scalar_Tensor",
         "_operator::__rshift__",
+        "aten::__rshift__.Scalar",
     )
 )
 def aten_bitwise_right_shift_int8(self: INT8, other: INT8) -> INT8: