add Webapp method and field

Change-Id: I7fd74729f908fa9c69deab35ef3dc5814bca1044
add isMiWifi method to WifiManager

N/A

Change-Id: Iebf48e65caca1d1a5b6b02732b167842866dfddc
Signed-off-by: mochangming <mochangming@xiaomi.com>