refactored controller, added employee detailed view

...pp/src/main/java/com/example/schedulerapp/Controller.java

...n/java/com/example/schedulerapp/EmployeeDetailsPopUp.java

.../src/main/java/com/example/schedulerapp/EmployeeView.java

...ulerApp/src/main/java/com/example/schedulerapp/Model.java

...p/src/main/java/com/example/schedulerapp/ScheduleApp.java

...in/resources/com/example/schedulerapp/employeeHeader.fxml

...ain/resources/com/example/schedulerapp/headerManager.fxml

...in/resources/com/example/schedulerapp/schedSidePanel.fxml

...urces/com/example/schedulerapp/staffManagerSidePanel.fxml