Log information about entering and leaving device scope

I was running some rendering examples and I was surprised to see some log messages stating that my device was being forced to Serial. Panicked, I opened up a debugger and set a breakpoint where the device was forced to Serial. Turns out, the device was forced to Serial inside of a ScopedRuntimeDeviceTracker (as part of the ColorTable operation). However, the log gave no indication that the default devices were restored.

To prevent further misunderstandings for myself and others, added some log messages to the ScopedRuntimeDeviceTracker to write when the scope is entered and left at the same logging level as that of the announcement that the device is forced.