core: add helper function to create events from expressions, move ak_user_has_authenticator to base evaluator

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

website/docs/policies/expression.mdx

@@ -29,23 +29,6 @@ ak_message("Access denied")
 return False
 ```
 
-### `ak_user_has_authenticator(user: User, device_type: Optional[str] = None) -> bool` (2021.9+)
-
-Check if a user has any authenticator devices. Only fully validated devices are counted.
-
-Optionally, you can filter a specific device type. The following options are valid:
-
--   `totp`
--   `duo`
--   `static`
--   `webauthn`
-
-Example:
-
-```python
-return ak_user_has_authenticator(request.user)
-```
-
 ### `ak_call_policy(name: str, **kwargs) -> PolicyResult` (2021.12+)
 
 Call another policy with the name _name_. Current request is passed to policy. Key-word arguments