add passreset routes

Introduced `get|post` `/passreset` routes. These routes mimic the
behavior of the existing PHP implementation, with the exception of
HTTP status code returns.

Routes added:
    GET /passreset
    POST /passreset

Routers added:
    aurweb.routers.accounts

* On an unknown user or mismatched resetkey (where resetkey must ==
  user.resetkey), return HTTP status NOT_FOUND (404).
* On another error in the request, return HTTP status BAD_REQUEST (400).

Both `get|post` routes requires that the current user is **not**
authenticated, hence `@auth_required(False, redirect="/")`.

+ Added auth_required decorator to aurweb.auth.
+ Added some more utility to aurweb.models.user.User.
+ Added `partials/error.html` template.
+ Added `passreset.html` template.
+ Added aurweb.db.ConnectionExecutor functor for paramstyle logic.
  Decoupling the executor logic from the database connection logic
  is needed for us to easily use the same logic with a fastapi
  database session, when we need to use aurweb.scripts modules.

At this point, notification configuration is now required to complete
tests involved with notifications properly, like passreset.
`conf/config.dev` has been modified to include [notifications] sendmail,
sender and reply-to overrides. Dockerfile and .gitlab-ci.yml have been
updated to setup /etc/hosts and start postfix before running tests.

* setup.cfg: ignore E741, C901 in aurweb.routers.accounts

These two warnings (shown in the commit) are not dangerous and a bi-product
of maintaining compatibility with our current code flow.

Signed-off-by: Kevin Morris <kevr@0cost.org>

test/test_user.py

@@ -28,8 +28,8 @@ def setup():
 
     setup_test_db("Users", "Sessions", "Bans")
 
-    account_type = session.query(AccountType).filter(
-        AccountType.AccountType == "User").first()
+    account_type = query(AccountType,
+                         AccountType.AccountType == "User").first()
 
     user = make_user(Username="test", Email="test@example.org",
                      RealName="Test User", Passwd="testPassword",
@@ -67,7 +67,7 @@ def test_user_login_logout():
     assert user.session.User == user
 
     # Search for the user via query API.
-    result = session.query(User).filter(User.ID == user.ID).first()
+    result = query(User, User.ID == user.ID).first()
 
     # Compare the result and our original user.
     assert result == user