Allow canvas applets to change frames

[marktaipan-cvisionai]

Category
Feature Request

Problem
Canvas applets are only displays current frame information and cannot change the video frame. The user has to leave the applet, change the frame, and reload the applet. This prevents some applet capabilities of denoting specific video frames for annotators to seek to.

Request
Allow a seekFrame event to be emitted by applets and listened to by the annotation page, that will force a goToFrame(...) call. This should not close the applet and the applet should have its frame information updated appropriately.