refactor: convert addUserToRoom to async (#28479)

apps/meteor/app/apps/server/bridges/rooms.ts

.../meteor/app/discussion/server/methods/createDiscussion.ts

apps/meteor/app/invites/server/functions/useInviteToken.js

...r/app/irc/server/irc-bridge/peerHandlers/joinedChannel.js

apps/meteor/app/lib/server/functions/addUserToRoom.ts

apps/meteor/app/lib/server/functions/setUsername.ts

apps/meteor/app/lib/server/methods/addUsersToRoom.js

apps/meteor/app/livechat/server/api/v1/room.ts

apps/meteor/app/meteor-accounts-saml/server/lib/SAML.ts

apps/meteor/app/slackbridge/server/SlackAdapter.js

apps/meteor/ee/server/lib/ldap/Manager.ts

apps/meteor/ee/server/lib/oauth/Manager.ts

...es/federation/infrastructure/rocket-chat/adapters/Room.ts

apps/meteor/server/services/team/service.ts