Track additional events

The goal is to eventually add tracking for the following actions:

* Click the "help" button at the top of the page
* Hover over the "more info" icons

This is an early review so that I can get early directional feedback before investing too heavily in a particular approach.
I'm looking for a more DRY way to do this... perhaps push the SEGMENT_IO_KEY setting into the context processor? I feel like we want it on every page...

Perhaps the tracking model could be built like so:

```html
initModelData.tracking = {
  segmentApplicationId: "{{ segment_io_key }}",
  page: "{{ view.page_name | default: ''}}"
}
```
Open to other ideas as well... maybe a `TrackedViewMixin` that injects this data into the context?