Re-surfacing total messages

[wcjord]

Linh/Paige and some other educators have expressed interest in total messages sent as a top-level progress metric.
Will is reluctant to surface this as 1) it doesn't feel like it gives learner choice in how they can achieve it and 2) could potentially encourage spamming.

Maybe we can address these concerns by making that number display how many messages that the user has a) sent OR b) unlocked via the toolbar activities.

This satisfies Linh’s desire to count messages sent while also giving learners choice in how to bump up that number, by demonstrating understanding of others messages OR producing their own, as they’re able at the time.