[Feature Request]: Refactor StorageFactory class to use registration functionality

[jgbradley1]

Do you need to file an issue?

• [x] I have searched the existing issues and this feature is not already filed.
• [x] My model is hosted on OpenAI or Azure. If not, please look at the "model providers" issue and don't file a new one here.
• [x] I believe this is a legitimate feature request, not just a question. If this is a question, please use the Discussions area.

Is your feature request related to a problem? Please describe.

Refactor and redesign the StorageFactory class in graphrag/graphrag/storage/facotry.py so that each storage type is registered with graphrag using the register() method.

The overall design should be similar to how the ModelFactory class is designed in graphrag/graphrag/language_model/factory.py.

Work on this was started in the branch joshbradley/refactor-storage-factory but was never completed.

All tests must pass for final approval.