Replace allowedNetworkTypes with allowedNetworkTypesForReason

- Replace getAllowedNetworkTypes with
getallowedNetworkTypesForReason(ALLOWED_NETWORK_TYPES_REASON_CARRIER)
- Replace "Settings.Global.PREFERRED_NETWORK_MODE" with
"getAllowedNetworkTypesForReason(USER)"
- Move EnabledNetworkModePreferenceControllerTest from robotests to unit
- Replace KEY_NR_ENABLED_BOOL with KEY_CARRIER_NR_AVAILABILITY_INT
- Rename PreferredNetworkModeContentObserver to AllowedNetworkTypesListener
Bug: 161434786
Test: build pass.
(PASS)atest CdmaSystemSelectPreferenceControllerTest
(PASS)atest PreferredNetworkModePreferenceControllerTest
(PASS)atest AllowedNetworkTypesListenerTest
(PASS)atest EnabledNetworkModePreferenceControllerTest
(PASS)atest MobileNetworkUtilsTest

Change-Id: I2b981569ad11cf70a558c1952cc2e077464328d8