This commit adds related_name parameter to UserGroup.direct_members
such that we can use direct_groups instead of the default
usergroupmembership_set for getting all the groups of which the
user is direct member.
This commit also sets related_name of UserGroupMembership.user_group
and UserGroupMembership.user_profile to "+" which means that we will
not be having backward relations for these. This change is correct
since we would need to use the recursive queries to get all the
groups of a user and all the members of a group after we add the
subgroups concept in next commit. This leads to us using direct_members
field of UserGroup instead of usergroupmembership_set in mention code,
but this will soon be replaced with the recursive query function to
include subgroup's members as well.
Extracted this commit from #19866.
Authored-by : Anders Kaseorg <anders@zulip.com>
Sahil Batra