Strings changes for opportunistic mobile networks

-Summary for opportunistic networks on multi-network header on the
 Network & internet home page. There are two strings we need here for
 when the network is configured but isn't being actively used: "In
 range" (e.g. we would be using it for data, but we already have a wifi
 connection) and "Not in range".

-Summary of the mobile data switch for opportunistic networks: "Phone
 will automatically switch to this carrier when in range".

Bug: 127529917
Bug: 128859152
Test: compile
Change-Id: I25e2f359790db6cfc328831c9bd06c172c9d9ad3