OpInfo: Add natural syntax for SampleInput creation (#85723)
Most SampleInput objects currently have no additional metadata,
meaning they have a 1:1 mapping with a normal function call. This adds
var arg forms of the `SampleInput` constructor such that you can just
call the `SampleInput` constructor as you would call the operator.
So, for example
```python
SampleInput(make_arg(shape), args=(2, 3), kwargs=dict(alpha=4))
```
becomes
```python
SampleInput(make_arg(shape), 2, 3, alpha=4)
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/85723
Approved by: https://github.com/mruberry
