Add a button to resolve and collapse recurring reminders

[scottleedavis]

Submitter: Ben S aka the Report Fairy
Email: bschaefer@collegenet.com
When a recurring reminder fires, it only provides options to snooze the alert. While this is functionally the same as Slack, the MM UX demands a response to the message, and there isn't something that just confirms it's been seen. (This is especially relevant for channel-wide reminders).

I propose a button titled "Complete" or "OK" that collapses the message, similarly to a normal, one-time reminder. This confirms that the reminder has been seen and resolves the need to interact with it.

Additional: channel-wide reminders should state who resolved a recurring reminder instance (related to existing report).