Create util for VoicemailProviderSetting operations.

This is mostly moving functionality from CallFeaturesSetting into a
utility class. I tried to tidy up some names/styling, but the logic
is unchanged.

These are essentially stand-alone functions which manipulate the
SharedPreferences for VoicemailProviderSettings. I considered adding
them as static methods on VoicemailProviderSettings, but since they
manipulate the storage of VoicemailProviderSettings at a different
level, it seemed like better organization to put them by themselves.

Bug: 17019623
Change-Id: I6d57dbc61d4eb07d0a433e83d82aaa2a9a96fd4e
diff --git a/src/com/android/phone/PhoneGlobals.java b/src/com/android/phone/PhoneGlobals.java
index 31337ee..55449d7 100644
--- a/src/com/android/phone/PhoneGlobals.java
+++ b/src/com/android/phone/PhoneGlobals.java
@@ -86,7 +86,7 @@
      *
      * ***** DO NOT SUBMIT WITH DBG_LEVEL > 0 *************
      */
-    /* package */ static final int DBG_LEVEL = 0;
+    public static final int DBG_LEVEL = 0;
 
     private static final boolean DBG =
             (PhoneGlobals.DBG_LEVEL >= 1) && (SystemProperties.getInt("ro.debuggable", 0) == 1);