Add reporting capability that allows clients to detect Flash elements in the courses loaded into their instance of Canvas

[chris_cajski]

Considering that Adobe is going to retire Flash at end-2020, it would be helpful if Canvas had a mechanism that would detect any Flash elements (e.g., SWFs) across all uploaded/published courses within an instance of Canvas.

On our end, we are currently being proactive in trying to make sure we don't have SWFs in our courses and that we publish to HTML5-only output, but it would definitely help if there was a way to run a check for Flash elements across everything in our instance of Canvas.

Thank you for considering this requested feature!