[frontend] Support for LTI Advantage 1.3

[anthonygego]

Is your feature request related to a problem? Please describe. LTI1.1 is deprecated since 2019/2020 and the consortium does not support it anymore since June 2022. Tools should migrate to LTI1.3.

Describe the solution you'd like Usage of this library can be considered : https://pypi.org/project/PyLTI1p3. It seems well maintained and it provides support for the Flask web framework.

Additional context This can probably be an opportunity to rethink (or throw, if flask is supported) the cookieless mechanism as it is a pain to maintain. It would be also cool to unify the way the public folder is served.