Add separate template for `flask-blueprints` flask doesn't have `APIRouter`

**Describe the bug**
While generating a flask app with FAAG. The Flask app is generated along with controllers related to FastAPI.

Example:
```python
some_route: APIRoute = APIRoute()
```

Since flask doesn't have `APIRoute` it instead has `blueprints`. Add a separate template or a logic that generates the controller as well based on the type of app.