[BUG] "MongooseModel" import missing in Ts.ED v8
### Describe the bug

After upgrading from Ts.ED v6 to v8, the following error occurs:

```
import { MongooseModel } from '@tsed/mongoose';
         ^^^^^^^^^^^^^
SyntaxError: The requested module '@tsed/mongoose' does not provide an export named 'MongooseModel'
```
It appears that MongooseModel is no longer exported in v8. The documentation does not provide an alternative or migration guidance.

![Image](https://github.com/user-attachments/assets/a336d752-806e-4ae8-adae-91591720dc4a)

### To Reproduce

1. Install @tsed/mongoose@8
2. Import MongooseModel in a service:

`import { MongooseModel } from '@tsed/mongoose';`

3. Run the application.

### Expected behavior

MongooseModel should be correctly exported, or an alternative should be provided in the documentation for migrating from v6 to v8.

### Code snippets

```TypeScript
Code Snippets (Before and After Upgrade)
Before (v6 - Working Code)

import { MongooseModel } from '@tsed/mongoose';

@Service()
export class UserService {
  @Inject(UserModel)
  private readonly userModel: MongooseModel<UserModel>;
}

After Upgrade (v8 - Broken Code)
import { MongooseModel } from '@tsed/mongoose'; // No longer exported
```

### Repository URL example

_No response_

### OS

ubuntu

### Node version

v22.13.0

### Library version

"@tsed/mongoose": "8.5.1",

### Additional context

_No response_