Android: Update Assessment Screen analytics

We previously added events for specific assessments related items, but we also need to add events just to mark the screen views themselves.

Additionally, since the Google Analytics "screen view" tags don't let us supply information besides a name, we've decided to add a regular event to accompany every "screen" event. This event will have:

Category: "screen"
Label: <screen name>
Action: <optional event specific data>

See iOS change here https://github.com/edx/edx-app-ios/pull/436/files#diff-dbd08a8519aa919edce557769b4c1f74R72

Here is the actual per screen event data:

Course List:
Label: “Course Dashboard”
Action: none
Course Outline:
Label: “Course Outline”
Action: none
Section Outline:
Label: “Section Outline”
Action: <section-name>
Scrolling Unit Detail:
Label: "Unit Detail"
Action: <unit-name>

For each of these we should also be sending a "course-id" property marking the course id. This will be set as a custom dimension on GA.

Acceptance criteria:

• Post a regular event, in addition to the trackScreen for each screen.

• Ensure that the 4 screens match the above description (Course Outline/Section Outline are the same Activity, but in different contexts)

• Ensure that course-id is sent with all those events as a property.