Updated access for managers in the contract module

When creating a new employment contract, the manager has access and receives notifications of the progress, is default signee and is displayed as manager in the contract details view.

Until now, we have used the manager of the person for whom the contract is created. We have now changed to using the manager of the department to which the position belongs.
In most cases it is the same person, but the change will make it more accurate in case of internal recruitment to another department or in cases where a person belongs to more than one department.

In addition we have removed the notification that a contract has been created to avoid too many emails.