Look up major database resources in a before_request hook.

A `before_request` hook queries the database for portfolios, requests,
and task orders based on the route arguments. The resources are added as
attributes on `g`. The portfolio context processor and the access
decorator now rely on those resources being available on `g`.

WIP: find major resources in before_request hook, apply to g

WIP: use g.portfolio for portfolio context processor

WIP: the access decorator should rely on the resources being available on g

tests/utils/test_context_processors.py

@@ -0,0 +1,24 @@
+from atst.utils.context_processors import get_resources_from_context
+
+from tests.factories import *
+
+
+def test_get_resources_from_context():
+    portfolio = PortfolioFactory.create()
+    task_order = TaskOrderFactory.create(portfolio=portfolio)
+    application = ApplicationFactory.create(portfolio=portfolio)
+    environment = EnvironmentFactory.create(application=application)
+
+    assert get_resources_from_context({"portfolio_id": portfolio.id}) == (portfolio,)
+    assert get_resources_from_context({"application_id": application.id}) == (
+        portfolio,
+        application,
+    )
+    assert get_resources_from_context({"environment_id": environment.id}) == (
+        portfolio,
+        application,
+    )
+    assert get_resources_from_context({"task_order_id": task_order.id}) == (
+        portfolio,
+        task_order,
+    )