Model import fix (ansible#646)

This fixes issue
[443](ansible#443).
Imports of AbstractUser are now inline in the functions that use it,
also added new import "annotations" in order to handle the functions
which had AbstractUser in type hints.

Please let me know if I need to add some additional information or if
something needs fixing, this is my first PR here!

Author: Kuppjaerk

ansible_base/lib/utils/models.py

@@ -1,12 +1,13 @@
+from __future__ import annotations
+
 import logging
 from dataclasses import asdict, dataclass
 from itertools import chain
-from typing import Optional
+from typing import TYPE_CHECKING, Optional
 
 from crum import get_current_user
 from django.conf import settings
 from django.contrib.auth import get_user_model
-from django.contrib.auth.models import AbstractUser
 from django.db import models
 from django.utils.translation import gettext_lazy as _
 from inflection import underscore
@@ -17,6 +18,10 @@
 
 logger = logging.getLogger('ansible_base.lib.utils.models')
 
+# Handle type hints of AbstractUser during linting
+if TYPE_CHECKING:
+    from django.contrib.auth.models import AbstractUser
+
 
 def get_all_field_names(model, concrete_only=False, include_attnames=True):
     # Implements compatibility with _meta.get_all_field_names
@@ -83,6 +88,8 @@ def is_system_user(user: Optional[models.Model]) -> bool:
     """
     Takes a model and returns a boolean if its a user whose username is the same as the SYSTEM_USERNAME setting
     """
+    from django.contrib.auth.models import AbstractUser
+
     system_username = get_system_username()[0]
     if user is None or not isinstance(user, AbstractUser) or system_username is None:
         # If we didn't get anything or that thing isn't an AbstractUser or system_username is not set set than what we have can't be the system user
@@ -95,6 +102,7 @@ class NotARealException(Exception):
 
 
 def get_system_user() -> Optional[AbstractUser]:
+
     from ansible_base.lib.abstract_models.user import AbstractDABUser
 
     system_username, setting_name = get_system_username()
@@ -142,6 +150,8 @@ def current_user_or_system_user() -> Optional[AbstractUser]:
 
 
 def is_encrypted_field(model, field_name):
+    from django.contrib.auth.models import AbstractUser
+
     if model is None:
         return False