LTI: Support Course dates substitution parameters

In this test, we're going to create a course with dates, and verify those dates are passed as ISO 8601 to the LTI through substitution parameters. pre-requisite LTI Advantage requires your site to be reachable from the internet. If not, Install ngrok to expose your moodle setup externally. Refer here for additional guidelines Have a course with an instructor. As admin install the LTI Robotest test app using the instructions found at https://robotest.theedtech.dev Make sure to set the custom parameters as indicated, in particular the $CourseSection.timeframe.begin and $CourseSection.timeframe.end since it will be the ones we will verify in this test. Tool configuration usage: Show in activity chooser and as preconfigured tool Enter a course as instructor Turn editing on Add external activity, choose Robotest app Click Select Content and Select one item (graded or not, does not matter) Save and Return to Course Set no course start date and no end course end dates Verify Launch the newly added link to the test app and verify the $CourseSection.timeFrame.begin and CourseSection.timeFrame.end says it's blank Edit the course settings and set both a start and end date for the course Launch the newly added link to the test app and verify the $CourseSection.timeFrame.begin and CourseSection.timeFrame.end and verify the dates match the course dates (dates are in ISO 8601 UTC time)