This commit does not add the logic of using this setting to actually
check the permission on the backend. That will be done in a later
commit.
Only owners can modify this setting, but we will add that logic in a
later commit in order to keep changes in this commit minimal.
Adding the setting breaks the frontend, since the frontend tries to find
a dropdown widget for the setting automatically. To avoid this, we've
added a small temporary if statement to `settings_org.js`.
Although, most lists where we insert this setting follow an unofficial
alphabetical order, `can_manage_all_groups` has been bunched together
with `can_create_groups` since keeping those similar settings together
would be nicer when checking any code related to creating/managing a
user group.
Shubham Padia