Remove `work_dir` argument from `ProviderService` methods

### Bug Description

The `ProviderService` class's `__init__` takes a `work_dir` argument, stored as `self._work_dir`. Some `ProviderService` methods use this, but others take their own `work_dir` and use that instead. This situation is confusing at best, a source of potential bugs at worst.

Ideally, all `work_dir` arguments to methods can be removed and replaced with `self._work_dir`. If some method(s) actually do need a different work dir, perhaps the argument should be named something different? Or if it truly should be called `work_dir` and methods need to take their own, comment(s) illuminating the situation should be added.

This same situation doesn't exist on other `service` classes.

### To Reproduce

`vi craft_application/services/provider.py`

Open craft_application/services/provider.py and inspect ProviderService.__init__ alongside every method that accepts or uses work_dir. Determine whether each method should rely on self._work_dir or needs a distinct, clearly explained argument; done means the inconsistency is resolved and any necessary exception is documented.

Written by the indexing model from the issue text.