feat: add support for LTI launch refactor in xblock-lti-consumer

This commit updates the sample LTI proctoring integration to use the new LTI launch refactor in xblock-lti-consumer (openedx/xblock-lti-consumer#288) and the Proctoring Services implementation (openedx/xblock-lti-consumer#297).

As a reminder, this application currently serves as a mock implementation of the proctoring flow to demonstrate how we might use the xblock-lti-consumer library for proctoring. It is not intended to be deployed as-is or to serve as an actual proctoring flow implementation.

Here is a digest of important changes.

* The launch_proctoring, start_assessment, public_keyset, and access_token views are removed.
* The start_proctoring and end_assessment views are added.
* A signal handler for the LTI_1P3_PROCTORING_ASSESSMENT_STARTED is added.
* The lti AppConfig is modified to support the above signal.

edx_exams/apps/lti/apps.py

@@ -6,5 +6,11 @@
 
 
 class LtiConfig(AppConfig):
+    """
+    AppConfig for lti Djangoapp.
+    """
     default_auto_field = 'django.db.models.BigAutoField'
     name = 'edx_exams.apps.lti'
+
+    def ready(self):
+        from edx_exams.apps.lti.signals import handlers  # pylint: disable=import-outside-toplevel,unused-import

edx_exams/apps/lti/signals/handlers.py

@@ -0,0 +1,13 @@
+"""
+edX Exams Signal Handlers
+"""
+from django.dispatch import receiver
+from lti_consumer.signals.signals import LTI_1P3_PROCTORING_ASSESSMENT_STARTED
+
+
+@receiver(LTI_1P3_PROCTORING_ASSESSMENT_STARTED)
+def assessment_started(sender, **kwargs):  # pylint: disable=unused-argument
+    """
+    Signal handler for the lti_consumer LTI_1P3_PROCTORING_ASSESSMENT_STARTED signal.
+    """
+    print(f"LTI_1P3_PROCTORING_ASSESSMENT_STARTED signal received with kwargs: {kwargs}")

edx_exams/apps/lti/urls.py

@@ -8,9 +8,6 @@
 
 app_name = 'lti'
 urlpatterns = [
-    path('start_proctoring', views.start_proctoring),
-    path('authenticate', views.authenticate),
-    path('start_assessment', views.start_assessment, name='start-assessment'),
-    path('end_assessment', views.end_assessment),
-    path('public_keyset', views.public_keyset),
+    path('end_assessment/<int:attempt_id>', views.end_assessment),
+    path('start_proctoring/<int:attempt_id>', views.start_proctoring, name='start_proctoring'),
 ]

edx_exams/apps/lti/utils.py

@@ -0,0 +1,11 @@
+"""
+LTI Utility Functions
+"""
+from django.conf import settings
+
+
+def get_lti_root():
+    if hasattr(settings, 'LTI_ROOT_URL_OVERRIDE'):
+        return settings.LTI_ROOT_URL_OVERRIDE
+    else:
+        return settings.ROOT_URL