Properly conditionalize "View Learner Devices" in Coach

[marcellamaki]

Observed behavior

develop regression
In Coach quizzes, the option to view LODs on the network is displayed, regardless of whether or not any LODs exist in the class.

Expected behavior

This option should only be there for LODs that exist. It is not an "are they on the network" check, but rather if any learners enrolled in the class are using LODs.

User-facing consequences

It is confusing for coaches to have this option (and to see learners as "disconnected" and not syncing when they really are not on LODs)

Steps to reproduce

1. Create a facility, users, and class where there is a coach and learner(s) but the learners are NOT on LODs
2. Go to the exams page
3. Observe that in the main exam page, and when clicking into a specific exam, see that the "View learner devices" link (and link to that page) is present.

Acceptance criteria

1. Implement that change in the ReportControls component to properly check if LODs exist
2. Cleanup any places where the learnerOnlyDevicesExist check is being used in the coach plugin that are no longer needed
3. If possible, have this code/check only written in one place, or in fewer places.

Context

develop

[rparadowski]

I can take it.

[marcellamaki]

Hi @rparadowski - I've assigned you. Let me know if you have any questions.