Add option to prevent reporter approving their own request

Summary

At the moment, a reporter can approve their own request if permission is given.

Example scenario

• There is a group of designated approvers to approve a particular request
• These approvers are also able to create requests which needs approval
• When this happens, they will be able to approve their own request

Suggestion

Have an option to choose whether or not reporters can approve their own request, or if the request must be approved by a different user