BE - Create separate module for legal api models

Moving forward, we plan to keep the [legal api models](https://github.com/bcgov/lear/tree/main/legal-api/src/legal_api/models) in a common business model module. We will move over to using the module fully when all the BE components have been upgraded to use the new models module.

BE components are still referencing the legal api models.

Here's [reference code](https://github.com/bcgov/lear/tree/feature-legal-name/python/common/business-registry-model) that we can use. As you can see, there's a new `business-registry-model` that has the legal api models. We need to do something similar here.

**TODOs**

- [ ] Create the module as an installable module (can use reference work)
- [ ] Grab all the models from Legal API and pull them in (can use reference work)
**Note: will probably need some tweaks as our models and sql-versioning will be different from legal name branch (legal name branch is extremely outdated)**
- [ ] Grab all the alembic migrations and we need to make sure they're working
- [ ] ~Grab the unit tests and pull them in and we need to make sure they're working~ _this will be done in https://github.com/bcgov/entity/issues/23164_