Fall-back to the old path.

Once the LMS has fully switched over to this new path [1],
we can remove the legacy (LMS) import support here.

- [1] https://github.com/edx/edx-platform/pull/27289

* Improve content presentation and add multiple content display support

This commit:
* Improves LTI content presentation handling, and correctly displays LTI DL content in the LMS
* Adds support for presenting multiple DL content items on the same block

* Addressing review comments

* Nits

* Improve test and fix issue

[BD-24][TNL-8072]

* Improve logging and error message presentation

* Add full deep linking content data on studio

* Internationalize LTI 1.3 templates

* Add translation tooling

Signed-off-by: Giovanni Cimolin da Silva <giovannicimolin@gmail.com>

* Update translations

* Address review comments

* Additional logging improvements

* Address review comments, fix test

Signed-off-by: Giovanni Cimolin da Silva <giovannicimolin@gmail.com>

Fix broken tests

Add serializer for `link` content type

This implements the endpoint that LTI tools use to return the deep linking configuration to the LMS, along with the `ltiResourceLink` type to allow testing with demo tool.

Signed-off-by: Giovanni Cimolin da Silva <giovannicimolin@gmail.com>

[BD-24] [TNL-7661] [BB-3172] LTI Improvements - Use declarative grading model on XBlock launch (#116)

* create default LineItem, WIP grade save

* add score to django admin

* WIP: find user and save grade to xblock

* boolean pragramatic grade interaction flag and optional params in enable_ags method

* Submit grades using grade signals

* lineitem urls should be optional

* lineitem is now readonly in declarative method

* test grade_submit called properly

* quality issue

* raise LTIError

* moved listener to signal.py, refactored models.py, added due and start date, updated tests.

* use load_block_as_anonymous_user and remove load_block, refactor tests

* refactor test to fix quality issue

* make lineitems_url required

* refactor tests, accept_grades_past_due on check

* test accept_grades_past_due

* add comma to last items

* refactor get_lti_ags_lineitems_url

* make sure crum returns user and not None

* nitpicks & use maximum score when given score is larger than maximum

* fix docstring of load_block_as_anonymous_user

* Move LTI 1.3 Key management to model

This:
- Removes the need to load the modulestore on every public keyset endpoint call.
- Simplifies the block structure and parent method overrides.
- Removes private key, client id and related parameters from XBlock fields

It also includes a migration from the data stored in the block to the model.

* Cleanup unused test helpers

* Version bump

* Addressing review comments

* BD-24 Implement LTI AGS Score Publish Service and Results Service

* Address PR comments and add more validation

* Address PR comments

* Add tests; Fix error with scoreMaximum; Fix quality issues; Adjust user_id results url slightly

* Add permissions tests and address other PR comments

* Fix quality test

* Address PR comments

* Add initial version of LineItem Implementation

Signed-off-by: Giovanni Cimolin da Silva <giovannicimolin@gmail.com>

* Adding tests

* Add LTI tests and fix quality isses

* Quality nit

* Add missing requirement, upgrade

* Squash migrations

* Fix merge conflicts

* Addressing review comments

* Add django url testing support

* Add tests to django views, implement compat layer

* Addressing review comments

* Improve tests and test descriptions

* Nit

* 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>

This commit adds support for the LTI 1.3 Access token endpoint, as detailed in the IMS Security Framework.
The token is generated using the consumer's private key (stored in the XBlock) after validating the message sent by the LTI Tool using it's public key.

Signed-off-by: Giovanni Cimolin da Silva <giovannicimolin@gmail.com>

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