Returns a page of the principals who have joined the chat, ordered by display name. Somebody with access who has not joined does not appear — they are not a member — and nor does somebody who has left. Members in every inbox state do appear, including those who have archived the chat: archiving is private and does not remove anybody from the listing everybody else sees.
Each row carries access_via, the grant by which that principal has access. The caller's own row comes back with an @type of me, carrying the favourite flag and inbox state that belong to them alone; other users are user and apps are app. Supply the optional type query parameter to restrict results to a single principal type.