* Implement extensions and view support for LTI

* Add missing iss to token

* Add missing requirement, upgrade requirements

* Improving comment

* Add missing exception statement

* Update lti_consumer/lti_1p3/tests/extensions/rest_framework/test_authentication.py

Co-authored-by: Ned Batchelder <ned@nedbatchelder.com>

Co-authored-by: Ned Batchelder <ned@nedbatchelder.com>

Features:
Implement LTI 1.3 launch support.
Add LTI 1.3 passthrough views as LMS plugins.