Add separated emergency option on power menu

 - Add a separated button on power menu to launch emergency dialer.
 - Change HardwareUiLayout.java FrameLayout to LinearLayout, let it can
display separated button.
 - Add a flag to recognize separated button should show/hide, if
EmergencyAffordance(India) enabled, separated button will hide,
otherwise power menu will display separated button & power
menu last item won't get white background.

Test: Manually, use "adb shell settings put global faster_emergency_phone_call_enabled 1" to show/hide separated emergency option, press emergency option will go to emergency dialer.
Change-Id: I1140fa412b655c16f3052cbabd118df278fd7f23
Merged-In: I8e6bb72ce7b8cecdb6bd01150b53f61f1515dbb1
Bug: 80376488