SysUser with mandatory unique Cooperator

Each SysUser record in GGCE should have a corresponding Cooperator record (1-1). Please update it to nullable = false and update liqibase.

Before adding the not-null constraint, liquibase needs to have a precondition check that all select count(sys_user_id) from sys_user where cooperator_id is null equals 0.

Also add a unique index on sys_user.cooperator_id, ensuring that each entry has its own Cooperator. Precondition select count(cooperator_id) from sys_user group by cooperator_id having count(cooperator_id) > 1 equals 0.

When this is ready, UI needs updating so that the list of users includes the link to Cooperator and the cooperator name.