Getting the Quiz ID when using Quiz Menu Placement for LTI Tool

[chrisrockwell]

When using the Quiz Menu placement in an LTI tool it doesn't seem like we can get the Quiz ID for the quiz in question.  We can get the course ID via variable substitution but it seems the only way to get the quiz id is by looking at the referrer header (not a good solution) because it looks something like domain.com/courses/36/external_tools/201?launch_type=quiz_menu&quizzes[]=55 <- that quizzes query parameter is what we need.

How do we get that?