Use Tsugi consumer

[xaviaracil]

Use Tsugi for managing the consumers instead of org.oscelot.lti-tool-provider

[xaviaracil]

Check if we have to extend tsugi for allowing the manage of consumer:

• Table creation
• Insert & Read of consumers

Modifiy the code in LtiLaunchController.launch to use Tsugi's OAuth Consumer classes

[lgekeler]

The Slack LTI must manage the creation of the account for the LMS user, as well as enrolling them in the slack team (course).
Since Slack uses an invitation strategy, the invitation has to be intercepted, replied to, the email address on file then changed back to the original user's, and the whole thing made seamless as any other LTI tool is. Does the vendor's API need fixing?