DEV: don't swallow a promise from group.findMembers method and switch to using async/await (PR #13888)

We found this problem when working on improving methods for adding and removing users from groups (see DEV: extract join_group method from groups#add_members method by AndrewPrigorshnev · Pull Request #13807 · discourse/discourse · GitHub).

This PR removes swallowing promises, switch some functions to using async / await and renames functions fromfindMembers to reloadMembers.

GitHub

Note this is a breaking change. There’s one private plugin I’m aware of that uses this method and will have to be updated. I’ve sent it to you via PM.

I’ve merged the fix into that plugin (and pinned plugin version), so I’m merging this.