This is required to fix an issue with the MM UI's error handling.
Previously, we only included the model source as a string. That could be an arbitrary URL, file path or HF repo id, but the frontend has no parsing logic to differentiate between these different model sources.
Without access to the type of model source, it is difficult to determine how the user should proceed. For example, if it's HF URL with an HTTP unauthorized error, we should direct the user to log in to HF. But if it's a civitai URL with the same error, we should not direct the user to HF.
There are a variety of related edge cases.
With this change, the full `ModelSource` object is included in each model install event, including error events.
I had to fix some circular import issues, hence the import changes to files other than `events_common.py`.
Refactor services folder/module structure.
**Motivation**
While working on our services I've repeatedly encountered circular imports and a general lack of clarity regarding where to put things. The structure introduced goes a long way towards resolving those issues, setting us up for a clean structure going forward.
**Services**
Services are now in their own folder with a few files:
- `services/{service_name}/__init__.py`: init as needed, mostly empty now
- `services/{service_name}/{service_name}_base.py`: the base class for the service
- `services/{service_name}/{service_name}_{impl_type}.py`: the default concrete implementation of the service - typically one of `sqlite`, `default`, or `memory`
- `services/{service_name}/{service_name}_common.py`: any common items - models, exceptions, utilities, etc
Though it's a bit verbose to have the service name both as the folder name and the prefix for files, I found it is _extremely_ confusing to have all of the base classes just be named `base.py`. So, at the cost of some verbosity when importing things, I've included the service name in the filename.
There are some minor logic changes. For example, in `InvocationProcessor`, instead of assigning the model manager service to a variable to be used later in the file, the service is used directly via the `Invoker`.
**Shared**
Things that are used across disparate services are in `services/shared/`:
- `default_graphs.py`: previously in `services/`
- `graphs.py`: previously in `services/`
- `paginatation`: generic pagination models used in a few services
- `sqlite`: the `SqliteDatabase` class, other sqlite-specific things
