Add ability to set call duration or end time in calendar and/or activities module

Add ability to set call duration or end time in calendar and/or activities module

Please add the ability to set the call duration or end time in the calendar and/or activities module. Although you can set the end time for an event, an event that is scheduled does not have the same fields as a call that is scheduled. Therefore, creating an event for each scheduled call is not a good solution to this problem.