This commit adds "Nobody" group option to system_user_groups_list in
settings_config.js. We do not allow can_remove_subscribers_group to
be set to "Nobody" group currently, but it is nice to add support
for this here since it will be used in more settings in future.
This commit refactors get_realm_user_groups_for_dropdown_list_widget
function to use "group_permission_settings" module instead of
passing variables like "allow_internet_group", etc. individually
for each settings.
We lose some test coverage due to this commit, but that would be
fixed when we add some more group-based settings and allow groups
other than system groups in the group based settings.
This lets us simplify the long-ish ‘../../static/js’ paths, and will
remove the need for the ‘zrequire’ wrapper.
Signed-off-by: Anders Kaseorg <anders@zulip.com>