Growth/Mentor dashboard

In the newcomer homepage project, we included a mentorship module which assigns a mentor to every newcomer, and gives them a button with which to easily ask a question to the mentor's talk page. It also lists the questions the newcomer has asked in the past, so they can easily return to those headings and look for answers. The mentors are drawn from a list of experienced editors who signed up to be mentors. Newcomers seem to appreciate the feature, and have asked thousands of mentor questions since it has debuted in May 2019.

Since the beginning of the feature, we have heard from mentors who want some way to know who their mentees are, and be able to proactively monitor and keep tabs on their progress in the wiki. For instance, we've heard this request from multiple communities at Wikimania 2019, from the Arabic and Czech Wikipedia community through their ambassadors, and here in Phabricator from the Serbian community.

The Growth team spent one day brainstorming, designing, and hacking on this idea. This page contains our notes so far.

User stories
These are needs that mentors have for the dashboard, based on our conversations with mentors from different communities:


 * I want to know how many mentees I have.
 * I want to know which of my mentees are doing the best on the wiki, so that I can encourage them, and which are doing the worst, so that I can help them.
 * I don't want to have to see the many mentees who are gone from the wiki, likely forever.
 * I want to proactively welcome, thank, and reward my mentees.
 * I want to see which of my mentees have asked me questions that I need to answer.
 * For a given mentee, I want to see how many edits they have, how many reverts they have, and how many thanks they have.
 * I want other mentors to see that I'm doing a good job as a mentor.
 * I want to be able to assign my mentees to someone else.
 * I want this to contain all the necessary mentor materials, like documentation and the ability to mark myself as temporarily inactive.

Functionality
We are thinking about this dashboard primarily containing a paginated list of mentees, along with some stats for each mentee. We will want mentors to be able to sort and filter the list, so as to see things like the most active mentees, the least active mentees, the most reverted mentees, etc. We want other parts of the page to contain useful information and tools for mentors, such as:


 * The way to mark yourself as temporarily inactive.
 * The way to claim mentees away from other mentors.
 * The way to change your introductory message.
 * News and guidance for how to be a good mentor.
 * Metrics on the mentor's own work, such as:
 * How many edits their mentees have accomplished.
 * How many thanks their mentees have gotten.
 * How many questions they have received and answered.