add Webapp method and field

Change-Id: Id9dac821517aaec3cc241b70226add4892e09e95
add isMiWifi method to WifiManager

N/A

Change-Id: I0a6430c1a67d9c9a8b2abef441c5ef843370826a
Signed-off-by: mochangming <mochangming@xiaomi.com>