Show notif when device reaches throttling temp

Adds logic to SystemUI that shows a notification alerting the user
that their phone has reached a certain temperature and has throttled
itself in order to cool down.

The logic is controlled by a configuration resource:
R.bool.config_showTemperatureWarning. If false, no action is taken.

When true, PowerUI checks every 30 seconds if the current temp of
HardwarePropertiesManager.DEVICE_TEMPERATURE_SKIN is greater than
the throttling temp of HardwarePropertiesManager.DEVICE_TEMPERATURE_SKIN.
If any one of the temperatures returned is greater, a notification is shown.

Clicking on the notification will show a dialog explaining more details
about what the device is doing in response to the high temperature.

The notification will disappear once the temperature drops below
the throttling temperature.

In order to check the temperature in SystemUI, HardwarePropertiesManager
has been updated to also allow any calls made by callers holding the
signature-level DEVICE_POWER permission.

Test: runtest systemui
Bug: 30995038

Change-Id: I1b3f122341911c68e90c8a49ad35267ac382b356
(cherry picked from commit b7caf1d0)