Shell: Allow usage of wifi usability score APIs

This permission is needed for wifi CTS tests.

Is the minimally scoped permission that needs to be added?
- Yes, this only allows the app to influnce wifi vs lte network
selection algorithm.

What options did you explore that did not need this permission?
- Without this permission, it would be impossible to test these API's:
WifiManager.setWifiConnectedNetworkScorer()
WifiManager.clearWifiConnectedNetworkScorer()
WifiManager.clearWifiConnectedNetworkScorer()
WifiManager.addOnWifiUsabilityStatsListener()

Bug: 150236894
Test: Device boots up.
Change-Id: Ic173e44ab818cdfecebde80715ddaec347019db6
Merged-In: Ic173e44ab818cdfecebde80715ddaec347019db6