Because the courseware microfrontend loads units inside iframes,
the LTI modal ends up being squished and generally ugly.
This PR introduces a new message sent to the parent window to request
a modal containing the contents of the LTI launch iframe.

https://openedx.atlassian.net/browse/TNL-7410

Also fixes a few untreated exceptions and remove unused variables.

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

Toggle aria-hidden attribute on modal window open/close; Set title attribute on iframe to display name of component; Remove aria-labelledby attribute from modal body; Make modal overlay id attribute unique'