Rename a bunch of mobile network files

1. Make them have "MobileNetwork" prefix
2. Also update WifiCallingPreference to remove its category
if it is invisible

Bug: 114749736
Test: RunSettingsRoboTests
Change-Id: I25871d579d6495e902e5583030889942ed2506a8
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 1ffdba1..8cad8a4 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -130,7 +130,7 @@
                        android:value="true" />
         </activity>
 
-        <activity android:name=".network.telephony.MobileSettingsActivity"
+        <activity android:name=".network.telephony.MobileNetworkActivity"
                   android:label="@string/network_settings_title"
                   android:theme="@style/Theme.Settings.Home"
                   android:launchMode="singleTask">