FEAT: Feature request to allow iterating over `FileChange` rather than `set[FileChange]`

Not sure how useful this would be broadly, but in my case I find it useful to apply `chain.from_iterable` to remove nesting in the code. Roughly:

```python
for change_type, change_path in chain.from_iterable(watch(some_path)):
   ...
```

It would be nice if `watch` had a kwarg, e.g. `unpack: bool`, where setting it to `True` would yield `FileChange` (rather than `set[FileChange]`).