chore: support multi-org group sync with runtime configuration (#14578)

- Implement multi-org group sync
- Implement runtime configuration to change sync behavior
- Legacy group sync migrated to new package

coderd/database/queries/groupmembers.sql

@@ -29,12 +29,41 @@ SELECT
 FROM
     groups;
 
+-- InsertUserGroupsByID adds a user to all provided groups, if they exist.
+-- name: InsertUserGroupsByID :many
+WITH groups AS (
+	SELECT
+		id
+	FROM
+		groups
+	WHERE
+		groups.id = ANY(@group_ids :: uuid [])
+)
+INSERT INTO
+	group_members (user_id, group_id)
+SELECT
+	@user_id,
+	groups.id
+FROM
+	groups
+-- If there is a conflict, the user is already a member
+ON CONFLICT DO NOTHING
+RETURNING group_id;
+
 -- name: RemoveUserFromAllGroups :exec
 DELETE FROM
 	group_members
 WHERE
 	user_id = @user_id;
 
+-- name: RemoveUserFromGroups :many
+DELETE FROM
+	group_members
+WHERE
+	user_id = @user_id AND
+	group_id = ANY(@group_ids :: uuid [])
+RETURNING group_id;
+
 -- name: InsertGroupMember :exec
 INSERT INTO
     group_members (user_id, group_id)