Prompt to start user before choosing a new ringtone

Dead users can't hear, nor see, ringtones. Let's wake them up and give
them a good shake first.

Until then, show a nice friendly "work profile isn't available" message.
Or depending on locale something confusing, egregious, and mismatched
like "work profile isn't available" instead.

Fix: 34735015
Bug: 34734809
Test: make RunSettingsRoboTests && make Settings && adb install -r $OUT/system/priv-app/Settings/Settings.apk && then reboot the device to see what happens
Change-Id: I86e61a7f3f654d7f38f04c43227a31e2f288e18f