WifiDataStall: Refactor for STA + STA

1. WifiDataStall should only monitor the primary STA since rssi polling
is not enabled for secondary STA.
2. WifiDataStall needs to reset state after MBB switch.
3. Use ActiveModeWarden to figure out if wifi is enabled or not.
4. Cache connection capabilities in ClientModeImpl to pass into
WifiDataStall.checkDataStallXXX(). Otherwise, we will need to store a
map of ClientMode to ConnectionCapabilites inside WifiDataStall to track
CMI when MBB is in progress (since rssi polling will switch to the new
primary CMM).

Bug: 181693252
Test: atest com.android.server.wifi
Change-Id: If6265594a314375f52d163af6dff0001066c8d88
5 files changed