telephony: Disable MSIM settings if unavailable

 * These activities share the same intent-filter as their non-MSIM
   counterparts. While this makes sense as a quick hack, it causes
   a UX issue when an app tries to launch one of these. An example
   is Google Voice- when it's time to update your voicemail settings,
   you're confusingly presented with a dialog asking to select
   which "com.android.phone" to use.
 * Disable the activities entirely if MSIM isn't available.

Change-Id: Iedeaf84f343ea0ee290275941cd55862a687800a