Replace node.meta source_fn with source_fn_stack (#210)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/210

A resubmit of https://github.com/pytorch/pytorch/pull/108447. Copy over the descriptions:

This is a follow-up of the discussion in https://github.com/pytorch/pytorch/pull/108356, where we want to repalce source_fn with source_fn_stack

Before this PR, for the following example:
```python
backend = EagerAndRecordGraphs()

torch.compile(backend=backend, fullgraph=True)
def cond_f(pred, pred2, x, y):
    def true_fn(pred2, x, y):
        return x + y

    def false_fn(pred2, x, y):
        def true_fn2(x, y):
            return x.sin() - y.cos()

        def false_fn2(x, y):
            return x.cos() - y.sin()

        return control_flow.cond(pred2, true_fn2, false_fn2, (x, y))

    return control_flow.cond(pred, true_fn, false_fn, (pred2, x, y))
```
The graph captured is shown below:
```python
class GraphModule(torch.nn.Module):
    def forward(self, L_pred_ : torch.Tensor, L_pred2_ : torch.Tensor, L_x_ : torch.Tensor, L_y_ : torch.Tensor):
        l_pred_ = L_pred_
        l_pred2_ = L_pred2_
        l_x_ = L_x_
        l_y_ = L_y_

        cond_true_1 = self.cond_true_1
        cond_false_1 = self.cond_false_1
        cond = torch.ops.higher_order.cond(l_pred_, cond_true_1, cond_false_1, [l_pred2_, l_x_, l_y_]);  l_pred_ = cond_true_1 = cond_false_1 = l_pred2_ = l_x_ = l_y_ = None
        return (cond,)

    class GraphModule(torch.nn.Module):
        def forward(self, l_pred2_, l_x_, l_y_):
            add = l_x_ + l_y_;  l_x_ = l_y_ = None
            return add

    class GraphModule(torch.nn.Module):
        def forward(self, l_pred2_, l_x_, l_y_):
            cond_true_0 = self.cond_true_0
            cond_false_0 = self.cond_false_0
            cond = torch.ops.higher_order.cond(l_pred2_, cond_true_0, cond_false_0, [l_x_, l_y_]);  l_pred2_ = cond_true_0 = cond_false_0 = l_x_ = l_y_ = None
            return cond

        class GraphModule(torch.nn.Module):
            def forward(self, l_x_, l_y_):
                sin = l_x_.sin();  l_x_ = None
                cos = l_y_.cos();  l_y_ = None
                sub = sin - cos;  sin = cos = None
                return sub

        class GraphModule(torch.nn.Module):
            def forward(self, l_x_, l_y_):
                cos = l_x_.cos();  l_x_ = None
                sin = l_y_.sin();  l_y_ = None
                sub = cos - sin;  cos = sin = None
                return sub
```
the source_fn for inner cond, sin, cos will be a (name, target) tuple:
```
('cond', <torch._ops.HigherOrderOperator object at xxx>)
('sin', 'sin')
('cos', 'cos')
('sub'. <built-in function sub>)
```

After this pr, the source_fn_stack will be a list of (name, target) tuple. The bottom of stack is the end of the list.
```
[('cond', <torch._ops.HigherOrderOperator object at xxx>), ('cond', <torch._ops.HigherOrderOperator object at xxx>)],
[('cond', <torch._ops.HigherOrderOperator object at xxx>), ('cond', <torch._ops.HigherOrderOperator object at xxx>), ('sin', 'sin')],
[('cond', <torch._ops.HigherOrderOperator object at xxx>), ('cond', <torch._ops.HigherOrderOperator object at xxx>), ('cos', 'cos')]
[('cond', <torch._ops.HigherOrderOperator object at xxx>), ('cond', <torch._ops.HigherOrderOperator object at xxx>), ('sub', <built-in function sub>)]
```

X-link: https://github.com/pytorch/pytorch/pull/108595

Test Plan:
See added tests in test_higher_order_ops.py and modify existing test.
Also updated bin by running:
"buck2 run @//mode/dev-nosan fbcode//aibench/api:gen_test_files --config client.id=nuclide"

cc voznesenskym penguinwu EikanWang jgong5 Guobing-Chen XiaobingSuper zhuhaozhe blzheng Xia-Weiwen wenzhe-nrv jiayisunx peterbell10 ipiszy ngimel yf225 chenyang78 kadeng muchulee8 aakhundov

Reviewed By: angelayi

Differential Revision: D48984986

Pulled By: ydwu4

fbshipit-source-id: 12beb1cee5c6a5b7dc976eda54baaa8f564a0f1e