getModelToken should be exported

[zaslavskyv]

getModelToken should be exported so that it's possible to provide stable test doubles.

Given service like this:

export class SomeService {
  constructor(@InjectModel(SomeEntity) private readonly container: Container) {}
}

What we have to do now:

Test.createTestingModule({
  providers: [
    SomeService,
    { provide: `${SomeEntity}AzureCosmosDbModel`, useValue: jest.mocked({}) },
  ],
});

How it should be:

Test.createTestingModule({
  providers: [
    SomeService,
    { provide: getModelToken(SomeEntity), useValue: jest.mocked({}) },
  ],
});