Create T-all zulip user group

This is needed to configure the infra announcement channel so the zulip
user group membership is synced automatically with project team
membership.

This notably does not include working groups, project groups, or marker
teams.

Author: jieyouxu

teams/all.toml

@@ -28,3 +28,9 @@ include-team-members = false
 extra-emails = [
     "rust-verification@googlegroups.com",
 ]
+
+[[discord-roles]]
+name = "WGs and Teams"
+
+[[zulip-groups]]
+name = "T-all"