Rail Power Monitor Addition for wifi

Change specifies a new wifi metric to be collected. There is a new power
monitor tool that will be for pre-production devices. With this monitor
it will better tell us what the power usage of the wifi subsystem
without having to estimate based off of the batter.

Bug: 115929961
Test: adb shell dumpsys batterystats
Results Examples:
        Energy consumed by wifi (mAh): 2.419736388888889
        Energy Rails consumed by wifi (mAh): 2.762777777777778

Change-Id: I14971e03d37dbabbb276d6c9ca717859f112165d