Better support runtime device selection in Timer

Previously, the Timer class only allowed you to either specify a device adapter tag on construction or a device id every time you get the elapsed time. This MR adds a couple of changes to make it easier to select a device at runtime. First, the constructor is changed to accept a DeviceAdapterId instead of a device adapter tag, which allows you to set the Timer's device when you don't know the device at compile time. Second, a form of the Reset method was added to allow you to change the device adapter being used.