Add Slices for WifiCalling
WifiCalling Slice Provider:
1. If there is no activation needed or if the Wifi calling
is currently turned on - provide the slice to toggle the
value
2. Else display appropriate message with further instructions
WifiCalling Slice Broadcast Receiver:
1. If the action is turning off wifi or if there is no
activation needed. Change the setting with ImsManager.
2. And Ask to requery the slice in one second to display
updated settings if 1 is valid or display appropriate message
Bug: 63731862
Bug: 78192106
Test: Use support-slices-demos-debug.apk to test on device
Test: Robotests
Change-Id: I29e1822fd24ebcff575fa48ad93f84ed91bf4d87
