[FEATURE] Add active/inactive unique maintainer count total/per repo visualizations to Maintainer Dashboard

[bshien]

Is your feature request related to a problem?

With the current code it is not possible to create visualizations that show active vs inactive unique maintainers(unique users that are maintaining at least one repo).

What solution would you like?

Add a map to the Maintainer Dashboard lambda which keeps track of whether unique maintainers are active or inactive and add each as a new document.

Do you have any additional context?

Part of #57