Introduce aggressive merge to `CapabilityPartitioner` (#100195)
With the old partitioner, suppose `add` is supported, the following code
```python
def fn(a, b, c, d):
x = a + b # add
y = c + d # add_1
return (x, y)
traced = symbolic_trace(fn)
partitioner = CapabilityBasedPartitioner(traced, supported_ops, allows_single_node_partition=True)
partitions = partitioner.propose_partitions()
```
results in the partitions `[[add], [add_1]]`. However, since these two partitions do not depend on each other, they can be aggressively merged into a single partition `[[add, add_1]]` without causing any issues. This PR introduces a new feature that allows such aggressive merging by introducing an option `aggressive_merge` to the Partitioner class.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/100195
Approved by: https://github.com/SherlockNoMad
