Use Wi-Fi state cache in Internet Panel

- The WifiManager.getWifiState() is a blocking API, It may not be
  suitable for use on the UI thread.

- Use the Wi-Fi state cache to avoid blocking the main thread of
  Internet Panel.

- If Wi-Fi is enabled, avoid setting Enable Wi-Fi again.

Bug: 223839177
Bug: 226039078
Test: manual test
atest -c InternetDialogControllerTest \
         InternetDialogTest \
	 com.android.systemui.qs.tiles.dialog.WifiStateWorkerTest

Change-Id: I74b05f05538e89472b26860e587f4f281d934908