With T310292: Allow admins to forcibly set a mentor's status, we allowed admins to set mentors' away status via Special:ManageMentors. We, however, did not add any API that would have the same capability.
Per @Trizek-WMF, ruwiki wants to be able to mark mentors as away via a bot/script. To make that possible, let's expand action=growthmanagementorlist to have that capability.
Acceptance criteria
- Admins are able to set away status via action=growthmanagementorlist API (ie. Special:ManageMentors's "Edit" button and API have equal capabilities)