Device do network scan after user rotates NetworkSelection page

Add the networkSelectSettings fragment into new activity, and set
the activity's android:configChanges as
"orientation|keyboard|keyboardHidden|screenSize|screenLayout
|smallestScreenSize".

Bug: 204039043
Test: atest AutoSelectPreferenceControllerTest (pass)
atest OpenNetworkSelectPagePreferenceControllerTest (pass)
atest NetworkSelectSettingsTest (pass)

Change-Id: Ic933c2294401bc50e105ddcfd2a17886d0bbefc3