Add learner_url to interactive_run_states (start of [#64338848])

When LARA loads an interactive using saved student data, it uses the versioned URL returned by Lab.

https://www.pivotaltracker.com/story/show/64338848
Sometimes use the LearnerURL for displaying interactive

[#64338848]

When LARA loads an interactive using saved student data, it uses the
versioned URL returned by Lab.  This commit checks to see if there is
a learner_url, and uses that if it exists.

https://www.pivotaltracker.com/story/show/64338848
Add a button to ‘Undo all my work’ – reloads authored Interactive.

[#64338848]

We need a way for students to restart their work from a fresh Interactive.
TODO:  I suspect we need to talk about the button label, and alert text.

https://www.pivotaltracker.com/story/show/64338848