[FastAPI] Refactor db modifications

For SQLAlchemy to automatically understand updates from the
external world, it must use an `autocommit=True` in its session.

This change breaks how we were using commit previously, as
`autocommit=True` causes SQLAlchemy to commit when a
SessionTransaction context hits __exit__.

So, a refactoring was required of our tests: All usage of
any `db.{create,delete}` must be called **within** a
SessionTransaction context, created via new `db.begin()`.

From this point forward, we're going to require:

```
with db.begin():
    db.create(...)
    db.delete(...)
    db.session.delete(object)
```

With this, we now get external DB modifications automatically
without reloading or restarting the FastAPI server, which we
absolutely need for production.

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

test/test_auth_routes.py

@@ -9,7 +9,7 @@ from fastapi.testclient import TestClient
 import aurweb.config
 
 from aurweb.asgi import app
-from aurweb.db import create, query
+from aurweb.db import begin, create, query
 from aurweb.models.account_type import AccountType
 from aurweb.models.session import Session
 from aurweb.models.user import User
@@ -32,9 +32,10 @@ def setup():
     account_type = query(AccountType,
                          AccountType.AccountType == "User").first()
 
-    user = create(User, Username=TEST_USERNAME, Email=TEST_EMAIL,
-                  RealName="Test User", Passwd="testPassword",
-                  AccountType=account_type)
+    with begin():
+        user = create(User, Username=TEST_USERNAME, Email=TEST_EMAIL,
+                      RealName="Test User", Passwd="testPassword",
+                      AccountType=account_type)
 
     client = TestClient(app)