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.
26 jobs for log-scoped-device in 0 seconds